Genesis 24:5-9

5The servant said to him, “Suppose the woman is not willing to follow me to this land; should I take your son back to the land from where you came?” 6Then Abraham said to him, “1Beware that you do not take my son back there! 72The Lord, the God of heaven, who took me from my father’s house and from the land of my birth, and who spoke to me and who swore to me, saying, ‘3To your 4descendants I will give this land’--He will send 5His angel ahead of you, and you will take a wife for my son from there. 8But if the woman is not willing to follow you, then you will 6be free of this oath of mine; 7only do not take my son back there.” 9So the servant 8placed his hand under the thigh of his master Abraham, and swore to him concerning this matter.