Brothers and sisters:
By faith Abraham obeyed when he was called to go out to a place that he was to receive as an inheritance; he went out, not knowing where he was to go.
By faith he received power to generate, even though he was past the normal age --and Sarah herself was sterile - for he thought that the one who had made the promise was trustworthy.
So it was that there came forth from one man, himself as good as dead, descendants as numerous as the stars in the sky and as countless as the sands on the seashore.
By faith Abraham, when put to the test, offered up Isaac, and he who had received the promises was ready to offer his only son, of whom it was said, “Through Isaac descendants shall bear your name.”
He reasoned that God was able to raise even from the dead, and he received Isaac back as a symbol.