The word of the Lord appeared to Abram in a vision.  Apparently Abram didn't exactly understand this vision and so God came to him in the flesh.

Often in Scripture we read these phrases, "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 promise or covenant is extremely significant.

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

Genesis 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 Abram.  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,(Matthew 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 Genesis15:17-21 include the land from the headwaters of the Euphrates River in Turkey all the way to the Persian Gulf and from there to Cairo in Egypt and from Cairo back to Turkey. (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.
Exodus 12:40 
And the time that the sons of Israel lived in Egypt was four hundred and thirty years.

Sarai apparently believes that she is not a part of  God's covenant with Abraham. When Sarai offered Hagar (daughter of the then-reigning Pharaoh by one of his concubines) to Abram, so that she and Abram 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 Believers in Jesus 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 the angel as God, as the "God who sees me".
Genesis 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 appears to Abraham and 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.
Philippians 3:3
For we are the circumcision who worship God in the spirit and rejoice in Christ Jesus and have no confidence in the flesh; 

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???