Genesis 17:17-21

‘Then Abraham fell on his face, and laughed, and said in his heart, “Shall a child be born to him who is a hundred years old, and shall Sarah who is ninety years old produce a child?” And Abraham said to God, “Oh that Ishmael might live before you”.'

The writer makes clear that Abraham's faith falters. He is clearly possessed with a mixture of emotions. At the words he expressly renews his attitude of obedient submission, he ‘falls on his face' (compare Genesis 17:3). But he laughs. The laughter may well be in his heart as are the words. The context shows that it means he is incredulous (compare Genesis 18:12). Whoever heard of such a thing?

(This was Abraham's view. It is of course possible for a hundred year old vigorous man to beget a child. Who can say what was possible with a healthy but barren 90 year old woman who was still vigorous and would live to 127, at a time when longevity was more the norm so that the ageing process was clearly slower? But we are told that her periods have ceased - Genesis 18:11. Whether this was to be a specific miracle or just an unusual scientific phenomena we are not told).

“Oh that Ishmael might live before you”. We cannot avoid the suggestion here that Abraham actually sees God as mistaken. Abraham himself has understandably lost hope. He does not want to have to wait any longer. He tells God that he is willing to accept Ishmael as the fulfilment of God's promise. How often we accept second best because the best seems impossible.

‘And God said, “No. Sarah your wife will bear a son, and you will call his name Isaac (which means ‘laughter')”. And I will establish my covenant with him for an everlasting covenant for his seed after him. And as for Ishmael, I have heard you. Behold I have blessed him and will make him fruitful, and will multiply him greatly. Twelve princes will he beget and I will make him a great nation. But my covenant will I establish with Isaac whom Sarah will bear to you at this set time in the next year”.'

God understands Abraham's doubts and confirms exactly what He has promised. Sarah will genuinely have a child of her own. The name ‘laughter' unquestionably has in mind the fact that Abraham laughed in his heart, but it also has in mind the joy that the child will bring, not only to Abraham and Sarah but to the world. His sceptical laughter will be turned into so great a joyous laughter, that in the end the first laughter is forgotten.

So the name Isaac signifies ‘do not doubt my promises' but it also means ‘from him blessings will abound'.

It is now made clear that the basic covenant for the chosen line is with Isaac. But this will withhold nothing from Ishmael. He too is part of the wider covenant and will produce a nation and be the father of rulers. Indeed he will parallel Isaac. Twelve rulers will descend from him. (Twelve was another number that contained within it the idea of tribal completeness. As we shall see later twelve was looked on as the ideal tribal confederation). Yet the use of ‘prince' (nasi) rather than ‘king' (melek) may hint at a slightly less exalted level of blessing, although alternately it may more reflect Ishmael's prophesied type of lifestyle (Genesis 16:12). Bedouins did not have ‘kings'. And it is only through Isaac that ‘all the nations of the world will be blessed' (Genesis 12:3).

God now commits Himself as to time. Abraham does not have long to wait. Isaac will be born in a year's time. This time note tallies with Genesis 17:1 demonstrating that this section is a genuine part of this whole covenant narrative and not a later insertion.