Ex 29:10

29:10 bring the bull. Priests laid their hands on the bull calf to symbolize personal identification and substitution in this sin offering. Blood was smeared on the horns of the altar of burnt offering as for laymen, since Aaron and his sons were still unconsecrated (Lev. 4:25, 30; cf. Lev. 4:7). The remainder of the blood was poured at the bottom of the altar as for a sin offering. Certain parts were to be burned on the altar (v. 13), but the remainder was to be burned outside the camp as unclean (v. 14).