The source for giving the compliment of yasher kochacha upon successful completion of a task is "ויברך אותם משה.” After the entire Mishkon was completed, Moshe blessed Bnei Yisroel. The Medrash points out that after Bnei Yisroel did everything they were supposed to do, Moshe Rabbeinu gave them a “Thank you.”
Building the Mishkon was not a voluntary accomplishment, so why were they deserving of any compliment. Haderash Veha’iyun writes that this is the fundamental principle in the concept of hakoras hatov. A person has an obligation to say thank you and yasher kochacha when he receives something, regardless of whether the person who gave or did something had no choice in the matter and was merely doing his duty.
The Rashash makes a similar observation based on the Mishnah in Sheviis, which explains that the poor, who are entitled to take the hefker crops during Shmittah, would go to the owner of the field and say, “Thank you.” The Rashash says that this is the source of the widespread practice to say yasher koach when the Kohen descends from the platform after duchening. The Kohen also does not really have any choice. If he would not duchen, he would be neglecting the fulfillment of his special mitzvah.
Teaching our children to say thank you is a common refrain and we constantly remind our children so that it becomes second nature to them. We should also teach them that saying thank you has nothing to do with the effort invested by the giver. It has to do with what one received. The circumstances that caused the giver to provide me with something do not diminish my obligation to thank him. This is the Jewish view of saying thank you.
Rabbi Gidon Goldberg
Head of School