A Good Gift in My Treasury Whose Name Is the Sabbath

Rav said: One who gives a gift to his fellow must inform him of it, as it is said, "to know that I am the LORD who sanctifies you." The Holy One, blessed be He, said to Moses: I have a good gift in My treasury, and its name is the Sabbath, and I wish to give it to Israel — go and inform them. From here Rabban Shimon ben Gamliel said: One who gives bread to a child must inform its mother. What does one do to the child? One smears it with oil and fills its eyes with kohl [as a visible mark]. And nowadays, when we are concerned about sorcery, one smears it with some of that same substance. Is that so? But Rav said: One who gives a gift to his fellow need not inform him, as it is said, "and Moses did not know that the skin of his face shone." This is not difficult: this case concerns a matter that will become known of itself, and that case concerns a matter that will not become known of itself. The Sabbath, too, will become known of itself! Its reward will not become known of itself.