Genesis 24:2-9 And Abraham said to his oldest servant of his house, that ruled over all that he had, Put, I pray you, your hand under my thigh:

AKJV⁽ⁱ⁾ ² And Abraham said to his oldest servant of his house, that ruled over all that he had, Put, I pray you, your hand under my thigh: ³ And I will make you swear by the LORD, the God of heaven, and the God of the earth, that you shall not take a wife to my son of the daughters of the Canaanites, among whom I dwell: ⁴ But you shall go to my country, and to my kindred, and take a wife to my son Isaac. ⁵ And the servant said to him, Peradventure the woman will not be willing to follow me to this land: must I needs bring your son again to the land from from where you came? ⁶ And Abraham said to him, Beware you that you bring not my son thither again. ⁷ The LORD God of heaven, which took me from my father's house, and from the land of my kindred, and which spoke to me, and that swore to me, saying, To your seed will I give this land; he shall send his angel before you, and you shall take a wife to my son from there. ⁸ And if the woman will not be willing to follow you, then you shall be clear from this my oath: only bring not my son thither again. ⁹ And the servant put his hand under the thigh of Abraham his master, and swore to him concerning that matter.