And he shall offer his offering unto the Lord, one he lamb of the first year without blemish for a burnt offering, and one ewe lamb of the first year without blemish for a sin offering, and one ram without blemish for peace offerings, (Numbers 6:14)
On the completion of the period of his vow he would return to his ordinary way of life, hence the need of a sin offering. The sin offering was normally offered before the burnt offering. The sin offering was for any omissions of which he may have been guilty during the days of his vow.
Peace offerings.
The Hebrew word here is of uncertain origin, and may be connected with the word “peace,” or with another meaning “to make restitution.” It is an offering for happy occasions, an offering of thankfulness, with the worshiper eating part of the sacrifice.