Numbers 5:15

15then he is to take his wife to the priest. He must also take an offering of a tenth of an ephah That is, probably about 3 1/2 pounds or about 1.6 kilograms of barley flour on her behalf. He must not pour olive oil on it or put incense on it, because it is a grain offering for jealousy, a reminder-offering to draw attention to wrongdoing.