NUM 15:3

3 you must offer to me special sacrifices which will be pleasing to me [when the priest burns them on the altar]. Some of them may be offerings that will be completely burned [on the altar]. Some of them may be to indicate that you have made a solemn promise to me. Some of them may be offerings that you yourselves have decided to make. Some of them may be offerings at one of the festivals that you celebrate each year. These offerings may be taken from your herds [of cattle] or from your flocks [of sheep and goats].