17:1 And when Abram was ninety nine years old - Full thirteen years after the birth of Ishmael. So long the promise of Isaac was deferred; Perhaps to correct Abram's over - hasty marrying of Hagar. That Abram and Sarai being so far striken in age, God's power in this matter might be the more magnified. The Lord appeared unto Abram - In some visible display of God's immediate glorious presence with him. And said, I am the Almighty God - By this name he chose to make himself known to Abram, rather than by his name Jehovah, Exo 6:3. He used it to Jacob, Gen 35:11. They called him by this name, Gen 28:5 43:14 48:3. It is the name of God that is mostly used throughout the book of Job, at least 30 times in the discourses of that book, in which Jehovah is used but once. After Moses, Jehovah is more frequently used, and this very rarely. I am El - Shaddai. It speaks the almighty power of God, either As an avenger, from wrv he destroyed, or laid waste; so some: and they think God took this title from the destruction of the old world: Or, As a benefactor, v for rva who, and yr it sufficeth. Our old English translation reads it here, very significantly, I am God All - sufficient. The God with whom we have to do, is self - sufficient; he hath every thing, and he needs not any thing. And he is enough to us, if we be in covenant with him; we have all in him, and we have enough in him; enough to satisfy our most enlarged desires; enough to supply the defect of every thing else, and to secure us happiness for our immortal souls. But the covenant is mutual, walk before me, and be thou perfect - That is, upright and sincere. Observe, That to walk before God, is to set God always before us, and to think, and speak, and act, in every thing as those that are always under his eye. It is to have a constant regard to his word, as our rule, and to his glory, as our end, in all our actions. It is to be inward with him in all the duties of religious worship, and to be entire for him in all holy conversation. That upright walking with God is the condition of our interest in his all - sufficiency. If we neglect him, or dissemble with him, we forfeit the benefit of our relation to him. A continual regard to God's all - sufficiency will have a great influence upon our upright walking with him.

Genesis 17:1 Parallel Commentaries

The Power of God
The next attribute is God's power. Job 9:19. If I speak of strength, lo, he is strong.' In this chapter is a magnificent description of God's power. Lo, he is strong.' The Hebrew word for strong signifies a conquering, prevailing strength. He is strong.' The superlative degree is intended here; viz., He is most strong. He is called El-shaddai, God almighty. Gen 17:7. His almightiness lies in this, that he can do whatever is feasible. Divines distinguish between authority and power. God has both. …
Thomas Watson—A Body of Divinity

Covenanting Performed in Former Ages with Approbation from Above.
That the Lord gave special token of his approbation of the exercise of Covenanting, it belongs to this place to show. His approval of the duty was seen when he unfolded the promises of the Everlasting Covenant to his people, while they endeavoured to perform it; and his approval thereof is continually seen in his fulfilment to them of these promises. The special manifestations of his regard, made to them while attending to the service before him, belonged to one or other, or both, of those exhibitions …
John Cunningham—The Ordinance of Covenanting

Confessing Christ an Indispensable Duty.
"--If we deny him, he also will deny us." This is predicated of Christ; and looks forward to the day when all mankind will stand before him as their judge. Denying Christ is here declared to be a mortal sin. Those found guilty of it will hear that sentence--"Depart ye cursed!" But this is to be understood only of a persevering denial of him. Those who turn by a timely repentance, will find mercy. This is true of every sin. But repentance may be too late. It must antecede death, or it will be of …
Andrew Lee et al—Sermons on Various Important Subjects