be a vow

Leviticus 22:18-21
"Speak to Aaron and his sons and all the Israelites and tell them, 'Any man of the house of Israel or any foreign resident who presents his offering, whether the burnt offering is a freewill gift or payment of a vow to the LORD, . . .

Leviticus 23:38
These offerings are in addition to the offerings for the LORD's Sabbaths, and in addition to your gifts, to all your vow offerings, and to all the freewill offerings you give to the LORD.

Numbers 15:3
and you present an offering made by fire to the LORD from the herd or flock to produce a pleasing aroma to the LORD--either a burnt offering or a sacrifice to fulfill a vow or as a freewill or festival offering--

Deuteronomy 12:6, 11, 17, 26
To that place you are to bring your burnt offerings and sacrifices, your tithes and heave offerings, your vow offerings and freewill offerings, as well as the firstborn of your herds and flocks. . . .

Psalm 66:13
I will enter Your house with burnt offerings; I will fulfill my vows to you--

Psalm 116:14, 18
I will fulfill my vows to the LORD in the presence of all His people. . . .

Nahum 1:15
Look to the mountains--the feet of one who brings good news, who proclaims peace! Celebrate your feasts, O Judah; fulfill your vows. For the wicked will never again march through you; they will be utterly cut off.

a voluntary

Leviticus 22:23, 29
You may present as a freewill offering an ox or sheep that has a deformed or stunted limb, but it is not acceptable to fulfill a vow. . . .

Deuteronomy 12:6
To that place you are to bring your burnt offerings and sacrifices, your tithes and heave offerings, your vow offerings and freewill offerings, as well as the firstborn of your herds and flocks.

Ezekiel 46:12
When the prince makes a freewill offering to the LORD, whether a burnt offering or a peace offering, the gate facing east must be opened for him. He is to offer his burnt offering or peace offering just as he does on the Sabbath day. Then he shall go out, and the gate must be closed after he goes out.

also the

Leviticus 19:5-8
When you sacrifice a peace offering to the LORD, you shall offer it for your acceptance. . . .