Esodo 29:1

And this [is] the thing that thou shalt do unto them to hallow them, to minister unto me in the priest's office: Take one young bullock, and two rams without blemish,

Ver. 1. Take one young bullock.] All sorts of sacrifices - sin offerings, burnt offerings, peace offerings - were to be offered for the priests, because of the special holiness and honour of their calling.