Shavua Tov. After Moshe accepts his mission to redeem the Jewish people from Egypt, he needs to ask permission from his father in-law, Yitro. He needed to be released from a previous oath that he had made.
Yitro agrees with Moshe’s request and wishes him well with the words, ״לך לשלום״, go to peace.
The Gemara at the end of מסכת ברכות, is very specific about saying לך לשלום and not לך בשלום, go IN peace that David wished his son Avshalom’s case.
Avshalom never made it safely as he is killed by Yoav when his hair was caught in the thicket.
It is customary to depart from a loved one at a funeral with the words לך בשלום. We are wishing the deceased eternal peace so that he will not need to come back in another carnation.
It may sound trivial but when we say good by to alive people, we say לך לשלום, but at a funeral we say, לך בשלום.