וַיֹּ֣אמֶר אַבְרָהָ֗ם אֶל־עַבְדּוֹ֙ זְקַ֣ן בֵּית֔וֹ הַמֹּשֵׁ֖ל בְּכָל־אֲשֶׁר־ל֑וֹ שִֽׂים־נָ֥א יָדְךָ֖ תַּ֥חַת יְרֵכִֽי׃
And Abraham said unto his servant, the elder of his house, that ruled over all that he had: ‘Put, I pray thee, thy hand under my thigh.
Read halakhic rulings (Jewish law) on Genesis 24:2: and classical halakhic sources.