Genesis 17:18

O that Ishmael might live before thee! - Abraham, finding that the covenant was to be established in another branch of his family, felt solicitous for his son Ishmael, whom he considered as necessarily excluded; on which God delivers that most remarkable prophecy which follows in Genesis 17:20, and which contains an answer to the prayer and wish of Abraham: And as for Ishmael I have heard thee; so that the object of Abraham's prayer was, that his son Ishmael might be the head of a prosperous and potent people.

Abraham seems up to this time to have regarded Ishmael as the promised seed. Hence, a feeling of anxiety instantly penetrates his breast. It finds utterance in the prayer, "Oh that Ishmael might live before thee." He asks "life" for his beloved son - that is, a share in the divine favor; and that "before God" - that is, a life of holiness and communion with God. But God asseverates his purpose of giving him a son by Sarah. This son is to be called Isaac - he that laughs or he shall laugh, in reference to the various emotions of surprise and delight with which his parents regarded his birth. Abram's prayer for Ishmael, however, is not unanswered. He is to be fruitful, beget twelve princes, and become a great nation. But Isaac is to be the heir of promise. At the present season next year he is to be born. The communication being completed, "God went" up from Abram.

17:18 And Abraham said, O that Ishmael might live before thee! — This he speaks nor as desiring that Ishmael might be preferred before the son he should have by Sarah, but as dreading lest he should be forsaken of God, he puts up this petition on his behalf. The great thing we should desire of God, for our children, is, that they may live before him, that is, that they may be kept in covenant with him, and may have grace to walk before him in their uprightness. God's answer to this prayer, is an answer of peace. Abraham could not say he sought God's face in vain.