When swearing is no private matter

I was part of an interesting discussion this morning about the etymology of the word testify and whether it is connected to testicles! The best discussion I could find online is at the Random House Word of the Day.
There it is suggested that there is no connection in Latin or Greek but there may be in Hebrew, going back ot Genesis 24:

²And Abraham said to his servant, the oldest of his household, who had charge of all that he had, "Put your hand under my thigh, ³that I may make you swear by the LORD, the God of heaven and God of the earth.

Any Old Testament experts want to weigh in?