Flavius Josephus, Antiquities of the Jews
William Whiston, A.M., Ed.

[222] Now Abraham greatly loved Isaac, as being his only begotten ¹ and given to him at the borders of old age, by the favor of God. The child also endeared himself to his parents still more, by the exercise of every virtue, and adhering to his duty to his parents, and being zealous in the worship of God. Abraham also placed his own happiness in this prospect, that, when he should die, he should leave this his son in a safe and secure condition; which accordingly he obtained by the will of God: who being desirous to make an experiment of Abraham's religious disposition towards himself, appeared to him, and enumerated all the blessings he had bestowed on him; how he had made him superior to his enemies; and that his son Isaac, who was the principal part of his present happiness, was derived from him; and he said that he required this son of his as a sacrifice and holy oblation. Accordingly he commanded him to carry him to the mountain Moriah, and to build an altar, and offer him for a burnt-offering upon it for that this would best manifest his religious disposition towards him, if he preferred what was pleasing to God, before the preservation of his own son.