Genesis 24:1-4

And Abraham was old, and well stricken in age: and Jehovah had blessed Abraham in all things. And Abraham said unto his servant, the elder of his house, that ruled over all that he had, Put, I pray thee, thy hand under my thigh: and I will make thee swear by Jehovah, the God of heaven and the God of the earth, that thou wilt not take a wife for my son of the daughters of the Canaanites, among whom I dwell: but thou shalt go unto my country, and to my kindred, and take a wife for my son Isaac.