Gen 17: God establishing an everlasting covenant with Abram, promising him a son and renaming him and Sarai

Abram was made the man of the covenant and promise. God promised that he should be the father of many nations through a son borne by Sarai, that He would be God to his seed, and would give them the land of the Canaanites. The seal of the covenant was circumcision.

• v1: More than thirteen years had passed since the initial promise of a descendant was made to Abram. This was perhaps to correct Abram's hasty marrying of Hagar and attempting to take matters into his own hands. Abram and Sarai were both older, and hence Abram and Sarai's faith would be tried, and God's power in this matter might be more magnified.
• God appeared and identified Himself as "God Almighty", or El-Shaddai. It bespeaks of the almighty power of God as an avenger, and as a benefactor who is sufficient. Some old translations render the verse as "I am God all-sufficient".
  
• v3: Abram fell on his face in the presence of God, as one overcome by the brightness of divine glory, as one in reverence and humility as he realised his unworthiness to be before God, as one worshipping and giving glory to God.
• v4: "As for me" - God, after declaring Himself, states that the covenant is one of His initiative, not man's.
  
• v4b: All believers in every age are looked upon as his spiritual seed, that he is the father of the faithful, and it is in light of this that we understand "the promise comes by faith, so that it may be by grace and may be guaranteed to all Abraham's offspring—not only to those who are of the law but also to those who are of the faith of Abraham. He is the father of us all. As it is written: "I have made you a father of many nations."He is our father in the sight of God, in whom he believed—the God who gives life to the dead and calls things that are not as though they were." (Rom 4:16-17).
• v5: Abram's name (Abram = exalted father) was changed to Abraham (= father of many). All believers too, have a new name (Rev 2:17: To him who overcomes, I will give some of the hidden manna. I will also give him a white stone with a new name written on it, known only to him who receives it) from God (Eph 3:15: from whom his whole family in heaven and on earth derives its name). The God who calls things that are not as though they were hence gave Abram a name which signified his promise, to encourage and confirm his faith.
• v7: The covenant was established, not to be altered or revoked, and was promised not only to Abraham but with his seed. The covenant of God's grace is everlasting, and it is transmitted with the seal of the Holy Spirit by which we are inwardly circumcised.
• v8: As the land of Canaan was secured to the seed of Abraham according to the flesh, so heaven is secured to all his spiritual seed by a covenant.
• v9-10: The covenant itself is called the "covenant of circumcision" (Acts 7:8). It was the covenant which Abraham and all his descendants must keep, as a copy or counterpart, as a sign and "seal of the righteousness that he had by faith" (Rom 4:11). Thus it not only confirmed the promises which were God's part of the covenant, but had with it an obligation upon Abraham and his seed to fulfil their own part of the covenant: to not only accept it, but to put away corruption of the flesh and observe all of God's commands.
• Circumcision was bloody, for all things by the law were purged with blood. Thank Jesus that by the shedding of His blood, all such ordinances are now abolished, and circumcision therefore gives way to baptism."In fact, the law requires that nearly everything be cleansed with blood, and without the shedding of blood there is no forgiveness"（Heb 9:22)
• Circumcision was of the foreskin, a part not exposed to the outside, for as Paul says, true circumcision is on the inside, not based on outward appearances.
• v14: The contempt of circumcision was a contempt of the covenant, hence the severe penalty.
• v15-16: God, years after telling Abraham that he would have a son, now told him that he would have a son by Sarai. The change of Sarai's name to Sarah, now signified a change from "my princess" to "a princess".
• v17: Abraham expressed great humility on the outside, but inwardly he laughed and thought God's promises impossible.
• v18: He hence spoke up for Ishmael, his son, making known his requests. (Phil 4:6: Do not be anxious about anything, but in everything, by prayer and petition, with thanksgiving, present your requests to God). Yet this request might have stemmed from his unbelief that Sarah would be able to bear a child at the age of ninety, thinking that if Ishmael was the one blessed, all questions and worries he had regarding a heir would be answered.
• v19, 21: Isaac means "he laughs". Although Abraham laughed inwardly, God knew, and hence here was his rebuke, to be reminded forever for his lack of faith. God's answer to Abraham was a "yes", but He reiterated that the covenant blessings were to be reserved for Isaac, and that nothing would change His ultimate plans.
• v20: Common blessings were secured to Ishmael, to multiply him.
• v23-27: Abraham's obedience to the law of circumcision. He did as God had said without asking why. God's will was not only a law to him, but a reason. We need to be at the level of obedience where God's will is not only what we live by, but is also the reason we live for. Abraham also circumcised himself and his entire household speedily, on the same day. "I will hasten and not delay to obey your commands." (Ps 119:60)