Leviticus 19:5
"And if ye offer a sacrifice of peace offerings unto the LORD, ye shall offer it at your own will."
Cross References (ranked by relevance)
But if the sacrifice of his offering be a vow, or a voluntary offering, it shall be eaten the same day that he offereth his sacrifice: and on the morrow also the remainder of it shall be eaten:
Ye shall offer at your own will a male without blemish, of the beeves, of the sheep, or of the goats.
And when ye will offer a sacrifice of thanksgiving unto the LORD, offer it at your own will.
If his offering be a burnt sacrifice of the herd, let him offer a male without blemish: he shall offer it of his own voluntary will at the door of the tabernacle of the congregation before the LORD.
Now when the prince shall prepare a voluntary burnt offering or peace offerings voluntarily unto the LORD, one shall then open him the gate that looketh toward the east, and he shall prepare his burnt offering and his peace offerings, as he did on the sabbath day: then he shall go forth; and after his going forth one shall shut the gate.
And the prince shall enter by the way of the porch of that gate without, and shall stand by the post of the gate, and the priests shall prepare his burnt offering and his peace offerings, and he shall worship at the threshold of the gate: then he shall go forth; but the gate shall not be shut until the evening.
And whosoever offereth a sacrifice of peace offerings unto the LORD to accomplish his vow, or a freewill offering in beeves or sheep, it shall be perfect to be accepted; there shall be no blemish therein.
And he sent young men of the children of Israel, which offered burnt offerings, and sacrificed peace offerings of oxen unto the LORD.
Either a bullock or a lamb that hath any thing superfluous or lacking in his parts, that mayest thou offer for a freewill offering; but for a vow it shall not be accepted.
And Hezekiah appointed the courses of the priests and the Levites after their courses, every man according to his service, the priests and Levites for burnt offerings and for peace offerings, to minister, and to give thanks, and to praise in the gates of the tents of the LORD.