Now Abraham was old, well advanced in age; and the Lord had blessed Abraham in all things.
So Abraham said to the oldest servant of his house, who ruled over all that he had, "Please, put your hand under my thigh,
and I will make you swear by the Lord, the God of heaven and the God of the earth, that you will not take a wife for my son from the daughters of the Canaanites, among whom I dwell;
but you shall go to my country and to my family, and take a wife for my son Isaac."
And the servant said to him, "Perhaps the woman will not be willing to follow me to this land. Must I take your son back to the land from which you came?"
But Abraham said to him, "Beware that you do not take my son back there.
The Lord God of heaven, who took me from my father's house and from the land of my family, and who spoke to me and swore to me, saying, 'To your descendants I give this land,' He will send His angel before you, and you shall take a wife for my son from there.
References for Genesis 24:7