Abraham was about to ask the servant to swear to do something. Putting his hand under Abraham's thigh would show that he would certainly do what he would swear to do. (See: [[rc://en/ta/man/translate/translate-symaction]])
The term "swear by" means to use the name of something or someone as the basis or power on which the oath is made. "promise me with Yahweh as your witness"
"the God of heaven and earth." The words "heaven" and "earth" are used together to mean every thing that God created. AT: "the God of everything in heaven and earth" (See: [[rc://en/ta/man/translate/figs-merism]])
"among whom I live." Here, "I" stands for Abraham and all of his family and servants. AT: "among whom we live" (See: [[rc://en/ta/man/translate/figs-synecdoche]])
# But you will go
This can be stated as a command. AT: "Swear that you will go" or "But go" (See: [[rc://en/ta/man/translate/figs-imperative]])