Genesis 17:17-21

Abraham fell facedown; he laughed and said to himself, "Will a son be born to a man a hundred years old? Will Sarah bear a child at the age of ninety?" And Abraham said to God, "If only Ishmael might live under your blessing!"
Then God said, "Yes, but your wife Sarah will bear you a son, and you will call him Isaac. I will establish my covenant with him as an everlasting covenant for his descendants after him. And as for Ishmael, I have heard you: I will surely bless him; I will make him fruitful and will greatly increase his numbers. He will be the father of twelve rulers, and I will make him into a great nation. But my covenant I will establish with Isaac, whom Sarah will bear to you by this time next year."

Some of us are content to live with the minimal blessings when God Almighty has set apart great blessings for us.
Abraham here is thinking of all the trouble he has to go through at age 99. In between all this overt laughter, Abraham is conveying a message to God. He’s telling God, “Forget it”. Just bless Ishmael and forget the other thing.
And God replied, “Get going son, I have already selected a name for your son and I have already set apart great many blessings for him and his descendants. So get to work.

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Dr. Johnson Cherian MD. PhD.