משנה אויף במדבר 5:26

He waves it, he brings it near [the altar], he takes a handful and he turns it into smoke, and then the remainder is eaten by the priests. He [first] gives [her the water] to drink, and then sacrifices her meal-offering. Rabbi Shimon says: he sacrifices her meal-offering and then gives her to drink, as it is said, “And afterward he shall make the woman drink the water” (Numbers 5:26), but if he gave her to drink and then sacrificed her meal-offering it is valid.