Genesis 24:2-9

2And Abraham said to his servant, the oldest of his household, who had charge of all that he had, “Put your hand under my thigh, 3that I may make you swear by the LORD, the God of heaven and God of the earth, that you will not take a wife for my son from the daughters of the Canaanites, among whom I dwell, 4but will go to my country and to my kindred, and take a wife for my son Isaac.” 5The servant said to him, “Perhaps the woman may not be willing to follow me to this land. Must I then take your son back to the land from which you came?” 6Abraham said to him, “See to it that you do not take my son back there. 7The LORD, the God of heaven, who took me from my father’s house and from the land of my kindred, and who spoke to me and swore to me, ‘To your offspring I will give this land,’ he will send his angel before you, and you shall take a wife for my son from there. 8But if the woman is not willing to follow you, then you will be free from this oath of mine; only you must not take my son back there.” 9So the servant put his hand under the thigh of Abraham his master and swore to him concerning this matter.