Genesis 24:9 in the King James Version
And the servant put his hand under the thigh of Abraham his master, and sware to him concerning that matter.
Context
8 If the woman isn’t willing to follow you, then you shall be clear from this oath to me. Only you shall not bring my son there again.”
9 The servant put his hand under the thigh of Abraham his master, and swore to him concerning this matter.
10 The servant took ten of his master’s camels, and departed, having a variety of good things of his master’s with him. He arose, and went to Mesopotamia, to the city of Nahor.