Genesis 24:2

He said to the chief servant in his household, the one in charge of all that he had, 'Put your hand under my thigh.

(New International Version)

Abraham said to his servant, the oldest of his household, who had charge of all that he owned, 'Please place your hand under my thigh,

(New American Standard Bible)

And Abraham said unto his eldest servant of his house, that ruled over all that he had, Put, I pray thee, thy hand under my thigh:

(King James Version)