Nicene and Post-Nicene Fathers, Vol. II:
City of God: Chapter 33

Chapter 33.—Of Rebecca, the Grand-Daughter of Nahor, Whom Isaac Took to Wife.

Isaac married Rebecca, the grand-daughter of Nahor, his father’s brother, when he was forty years old, that is, in the 140th year of his father’s life, three years after his mother’s death.  Now when a servant was sent to Mesopotamia by his father to fetch her, and when Abraham said to that servant, “Put thy hand under my thigh, and I will make thee swear by the Lord, the God of heaven, and the Lord of the earth, that thou shalt not take a wife unto my son Isaac of the daughters of the Canaanites,” 948 what else was pointed out by this, but that the Lord, the God of heaven, and the Lord of the earth, was to come in the flesh which was to be derived from that thigh?  Are these small tokens of the foretold truth which we see fulfilled in Christ?

Footnotes

Gen. 24:2, 3.