Genesis 24:3

24:3 so that I may make you solemnly promise by the Lord, the God of heaven and the God of the earth: You must not acquire a wife for my son from the daughters of the Canaanites, among whom I am living.

Genesis 24:9

24:9 So the servant placed his hand under the thigh of his master Abraham and gave his solemn promise he would carry out his wishes.