Genesis 24:1-4

Now Abraham was old, [well] advanced in age; and the LORD had blessed Abraham in all things. Abraham said to his servant [Eliezer of Damascus], the oldest of his household, who had charge over all that Abraham owned, “Please, put your hand under my thigh [as is customary for affirming a solemn oath], [Gen 15:2] and I will make you swear by the LORD, the God of heaven and the God of earth, that you will not take a wife for my son from the daughters of the Canaanites, among whom I live, but you will [instead] go to my [former] country (Mesopotamia) and to my relatives, and take a wife for my son Isaac [the heir of the covenant promise].”