The Covenant God made with Abraham begins a series of covenants that impact all of world history even to modern times. The details of that covenant matter. This article tracks each promise leading to the covenant God made with Abraham.
This covenant did not actually start with a formal covenant in the normal biblical sense. It started with a series of smaller promises. Considering that God is perfect, we know that he keeps his promises, we know that even from the start, everything he says to Abraham, everything God says he will do, that God is going to do them. So, we can start this exploration early in Abraham's life. The first reference of a promise to Abraham, at the time known as Abram, is found in Genesis 12:
1The LORD had said to Abram, "Leave your country, your people and your father's household and go to the land I will show you. 2"I will make you into a great nation and I will bless you; I will make your name great, and you will be a blessing. 3I will bless those who bless you, and whoever curses you I will curse; and all peoples on earth will be blessed through you."
4So Abram left, as the LORD had told him; and Lot went with him. Abram was seventy-five years old when he set out from Haran. (Genesis 12:1-4 NIV)
1Now the Lord had said unto Abram, Get thee out of thy country, and from thy kindred, and from thy father's house, unto a land that I will shew thee: 2And I will make of thee a great nation, and I will bless thee, and make thy name great; and thou shalt be a blessing: 3And I will bless them that bless thee, and curse him that curseth thee: and in thee shall all families of the earth be blessed.
4¶So Abram departed, as the Lord had spoken unto him; and Lot went with him: and Abram was seventy and five years old when he departed out of Haran. (Genesis 12:1-4 KJV)
1Yahvah said to Abram,
Depart from your land and from the place of your nativity and from the house of your father to the land which I will show you 2and I will make you into a great people and I will bless you and make your name great and you will be a blessing. 3I will bless those who bless you and curse those who curse you and
in you all the families of the land will be blessed.
4Abram did as Yahvah had spoken to him and Lot went with him. Abram was 75 years old when he departed from Haran. (Genesis 12:1-4 BRB)
This promise contains several parts that we will see again. Some parts will remain as is, others will grow and change. In this promise we see the following:
Great Nation Abraham is to be made into a great nation. A single nation. One with many people in it.
Blessed Abraham will be blessed.
Name to be Great His name is to be great. He will be known by many people. The name of someone biblically represents his authority. This passage is saying that Abraham will have great authority in the world.
Be a Blessing Abraham will be a blessing to others. Those around him, his family, people he knows.
Blessing/Curses Those that bless Abraham will in turn be blessed by God, those that curse Abraham will in turn be cursed by God.
All peoples Blessed Through Abraham all peoples on earth will be blessed.
The last entry on this list, probably because it will happen later in time, is generally thought to be a reference to the New Covenant and the covenant through which everyone is blessed. The others, though, are just promises being made to Abraham himself and his decedents.
This is just the start. As Abraham demonstrates faith, the covenant changes. We look now at the next round of covenant making with Abraham.
Firepot Covenant with Abraham
If the promises of God were not enough, they multiply as we go further up the record. By chapter 15 of Genesis we find the promises have multiplied greatly. The following are the relevant passages.
15and let them be lights in the expanse of the sky to give light on the earth." And it was so. (Genesis 1:15 NIV)
15And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so. (Genesis 1:15 KJV)
Let them be for lights in the firmament of the skies to give light on the land,and it was so. (Genesis 1:15 BRB)
Here the number of offspring has been increased. It is now likened to the stars in the sky. If, indeed, they can be counted. This is substantially larger than just a large nation, which we saw in Chapter 12.
Now the story turns its attention to making this into a covenant, instead of just a promise. Abraham is asked to prepare the sign for the covenant, and then when it was time.
17When the sun had set and darkness had fallen, a smoking firepot with a blazing torch appeared and passed between the pieces. 18On that day the LORD made a covenant with Abram and said, "To your descendants I give this land, from the river of Egypt to the great river, the Euphrates -- 19the land of the Kenites, Kenizzites, Kadmonites, 20Hittites, Perizzites, Rephaites, 21Amorites, Canaanites, Girgashites and Jebusites." (Genesis 15:17-21 NIV)
17¶And it came to pass, that, when the sun went down, and it was dark, behold a smoking furnace, and a burning lamp that passed between those pieces.a burning…: Heb. a lamp of fire 18In the same day the Lord made a covenant with Abram, saying, Unto thy seed have I given this land, from the river of Egypt unto the great river, the river Euphrates: 19The Kenites, and the Kenizzites, and the Kadmonites, 20And the Hittites, and the Perizzites, and the Rephaims, 21And the Amorites, and the Canaanites, and the Girgashites, and the Jebusites. (Genesis 15:17-21 KJV)
17It came to pass that when the sun had set and it was dark there appeared a smoking furnace and a fiery torch that passed between these halves. 18In that day Yahvah made Abram a contract saying, To your seed I will give this land from the river of Mizraim to the great river, the river Euphrates, 19to the Kenites and to the Kenizzites and to the Kadmonites 20and to the Hethites and to the Perizzites and to the Rephaites 21and to the Amorites and to the Canaanites and to the Girgashites and to the Jebusites. (Genesis 15:17-21 BRB)
The symbolism of this event is often overlooked. Normally, both parties entering into a contract would walk between the pieces together. Symbolizing the covenant and reiterating that if either party broke their part of the bargain, the other had the right to cut the offender into two, just like the animals had been.
In this case Abraham is noticeably absent. Only the firepot passes between the pieces. What does this signify? That God alone had passed through the pieces, and that if God failed to keep his part of the covenant, that he could be cut into pieces, but that Abraham was under no such threat. This pictured what was now an unconditional promise.
Would Abraham ever have to execute this threat? No. God is trustworthy. He keeps his promises. This entire picture is simply for Abraham's benefit, and ours, so that we understand this has the force of a full contract, like two people might enter into. But, unlike a human counterpart, God will not fail in keeping his side of the bargain.
What does that promise involve? In addition to what was mentioned before, it now included many more offspring, and it included a piece of land, the land from the border of Egypt to the Euphrates.
When God established the Sinai covenant he would make claim to this territory conditional on the good behavior of the nation, but for the purposes of all time, this is Abraham's territory. 
As the nation would later experience, as they disobeyed God and his later covenant of possession, the farthest parts of this empire would be the first to fall.  As the nation would later disobey that covenant, the nation would itself be cut in two, like that pictured in this vision.
This was not the end of the story in Abraham's day. God switched to a conditional promise, and increased it still.
More Covenant with Abraham
As Abraham's story unfolds in Genesis we see it increasing still. The next relevant passages are found in Genesis 17. The following is the relevant text:
3And Abram fell on his face: and God talked with him, saying,
4¶As for me, behold, my covenant is with thee, and thou shalt be a father of many nations.many…: Heb. multitude of nations 5Neither shall thy name any more be called Abram, but thy name shall be Abraham; for a father of many nations have I made thee.Abraham: that is, Father of a great multitude 6And I will make thee exceeding fruitful, and I will make nations of thee, and kings shall come out of thee.
7¶And I will establish my covenant between me and thee and thy seed after thee in their generations for an everlasting covenant, to be a God unto thee, and to thy seed after thee. 8And I will give unto thee, and to thy seed after thee, the land wherein thou art a stranger, all the land of Canaan, for an everlasting possession; and I will be their God.wherein…: Heb. of thy sojournings
9¶And God said unto Abraham, Thou shalt keep my covenant therefore, thou, and thy seed after thee in their generations. 10This is my covenant, which ye shall keep, between me and you and thy seed after thee; Every man child among you shall be circumcised. (Genesis 17:3-10 KJV)
3Abram fell facedown, and God said to him, 4"As for me, this is my covenant with you: You will be the father of many nations. 5No longer will you be called Abram; your name will be Abraham, for I have made you a father of many nations. 6I will make you very fruitful; I will make nations of you, and kings will come from you. 7I will establish my covenant as an everlasting covenant between me and you and your descendants after you for the generations to come, to be your God and the God of your descendants after you. 8The whole land of Canaan, where you are now an alien, I will give as an everlasting possession to you and your descendants after you; and I will be their God."
9Then God said to Abraham, "As for you, you must keep my covenant, you and your descendants after you for the generations to come. 10This is my covenant with you and your descendants after you, the covenant you are to keep: Every male among you shall be circumcised. (Genesis 17:3-10 NIV)
3Abram fell on his face. God talked with him saying, 4As for me, I am establishing my contract with you and you will be a father of many peoples. 5FM
Your name will not be Abram any longer, but your name will be Abraham for6I will make you fruitful and multiply you exceedingly and I will make you a father of many peoples and kings will come out of your loins. 7I will establish my contract between me and you and your seed after you throughout their generations for a contract to eternity and I will be god to you and to your seed after you. 8
I have made you a father of many peoples.
I will give to you and your seed after you the land in which you now reside temporarily, all the land of Canaan, for an inheritance to eternity,and I will be their god.
God said to Abraham, You will preserve my contract, you and your seed after you throughout their generations. 10(Genesis 17:3-10 BRB)
This is my contract which you will preserve between me and you and your seed after you, every male among you will be circumcised.
Here the promise grows still larger. Now Abraham is to become many nations which is mentioned twice and he is to be the father of kings and the whole land of Canaan is to become his as well.
Unlike the earlier promises, Abraham has a condition. He, and his household, must be circumcised. This is his part of this conditional promise. Abraham is faithful and does what God asks, and so keeps his side of the promise. God is now doing more than he would at first.
At this point we should stop and ask what has been fulfilled from this set of promises. The king, or kings, which would come from Abraham, are those who populate the house of David, some 1000 years later. 1000 years after that Jesus comes from David's line and will eventually permanently fulfill the king promise given here to Abraham.
What about the other promises? Especially, here, the promise of many nations? This is harder to find fulfillment of, but it is what we are actually headed for in this section. We must wait a little longer before we can reveal just how that is fulfilled. Let me say now, though, that the Jewish nation, those we today call the modern nation of Israel, were never more than one nation, not many nations as promised here. Abraham's decedents must include someone else.
God Swears by Himself
As we follow the story still further, the promises we've seen so far become completely unconditional. God is pleased with Abraham. The story involves a test, a test where Abraham is asked to sacrifice his son, his only son. Foreshadowing the cross, and God's sacrifice of his only son, Abraham obeys and travels to the region of Moriah where he nearly completes the test. At the last moment, the Lord provides a Ram to substitute and then confirms the covenant:
15The angel of the LORD called to Abraham from heaven a second time 16and said, "I swear by myself, declares the LORD, that because you have done this and have not withheld your son, your only son, 17I will surely bless you and make your descendants as numerous as the stars in the sky and as the sand on the seashore. Your descendants will take possession of the cities of their enemies, 18and through your offspring all nations on earth will be blessed, because you have obeyed me." (Genesis 22:15-18 NIV)
15¶And the angel of the Lord called unto Abraham out of heaven the second time, 16And said, By myself have I sworn, saith the Lord, for because thou hast done this thing, and hast not withheld thy son, thine only son: 17That in blessing I will bless thee, and in multiplying I will multiply thy seed as the stars of the heaven, and as the sand which is upon the sea shore; and thy seed shall possess the gate of his enemies;shore: Heb. lip 18And in thy seed shall all the nations of the earth be blessed; because thou hast obeyed my voice. (Genesis 22:15-18 KJV)
15The king of Yahvah called to Abraham from the skies a 2nd time. 16He said, I have sworn by myself, says Yahvah, because you have done this thing and have not kept your son, your only one, from me, 17
I will surely bless you. I will surely multiply your seedas the stars of the skies and as the sand which is on the sea shore and your seed will inherit the lands of their enemies. 18In your seed all the peoples of the land will be blessed because you have obeyed my voice. (Genesis 22:15-18 BRB)
"I swear by myself," is strong language for God. Nothing is going to stop him doing as he promised to Abraham. Nothing of the things we've looked at here are going to fail to come to pass. Unconditionally. Without any chance to fail.
Compared to the New Covenant, this covenant no longer has any conditions placed on Abraham or his family. It is also not the New Covenant, in that it does not lead to eternal life. This covenant is only hinted at in these passages, and Hebrews 11 demonstrates that Abraham is saved under the New Covenant, but that covenant awaits the arrival of Jesus before it is in view.
At this point there is no further covenant making with Abraham's sons. God does, though, come along and confirm this covenant with later generations in his family. We now turn our attention to the next generation, Isaac.
1. Deuteronomy 11:22-46
2. 2 Samuel 8:3
3. 2 Chronicles 18:3