The word of the Lord appeared to Abram in a vision.  Apparently Abram didn't exactly  understand and so God came to him in the flesh. Who is "the word of the Lord" and "the angel of the Lord"? In many instances in Scripture these two phrases are synonymous for the Son of God, the pre-incarnate Jesus. Abram asks God for a sign of His promise to bless Abram's descendants. This covenant is extremely significant.

God prepares a covenant with Abram.  The commentator gives an excellent summary of the significance of this covenant agreement.

Gen 15:11
Then birds of prey came down on the carcasses, but Abram drove them away.
There is a profound spiritual truth application for us today from this verse.  These birds of prey represent Satan and his desire to stop this covenant between God and Abraham.  Satan tries to destroy the promises of God.  Abram was quick to drive these birds away.  Believers should recognize the surety of God's promises and be quick to defend them. The Septuagint (Greek Old Testament) records that Abram "sat with" the animal carcasses.  Application for us...guard God's promises!  See also the parable of the soils,(Matt 13:3-8).

The prophet Jeremiah in Jeremiah 34:17-20 reminds the people of God's covenant with Abraham and the consequences of violating that covenant.

God promises Abram the land, not the land of Israel as we know it today. These borders listed in Gen. 15:17-21 include the land from Baghdad to Cairo and from Turkey to the Persian Gulf. (Email us for a map of the boundaries of this land) All Abram had to do was to walk the land and claim it. Again, did Abram obey? NO.

God also tells Abram that his descendants will be enslaved and mistreated four hundred years. And so they were.
Exo 12:40
And the time that the sons of Israel lived in Egypt was four hundred and thirty years.

When Sarai offered Hagar to Abraham, so that she and Abraham could have a child, she was trying to "help God out". Sarai was doing what was culturally acceptable but it was morally wrong. How often do we as Christians do and say things that are acceptable by the world, but wrong by God's standards?

Notice when Hagar runs away, the angel of the Lord promises her something. "I will so increase your descendants that they will be too numerous to count." Does a simple angel have this kind of power? Hagar knew who this angel was. She identifies him as God, as the "God who sees me".
Gen. 16:13.

Again Abram didn't trust God or wait patiently on Him. And look what happened. If Abram had trusted God to take care of him during the famine and had not gone to Egypt, there would have been no Hagar and no Ishmael.

God institutes the sign of circumcision as a confirmation of His covenant and He changes the names of Abram and Sarai.  When there is a change in name, it signifies a change in character. This circumcision is a foreshadowing of circumcision of the heart.

Notice also that Isaac was not conceived until after Abraham's circumcision. And God makes it clear to Abraham that His covenant is with Isaac and not Ishmael.

Lessons to be learned from Abraham? If only we would obey God completely and trust Him completely and wait patiently on Him, life would be so much easier, wouldn't it???