Vows were Made in Reference to Offering Sacrifices
Source: TTT
Leviticus 7:16
If, however, the sacrifice he offers is a vow or a freewill offering, it shall be eaten on the day he presents his sacrifice, but the remainder may be eaten on the next day.
Leviticus 22:18, 22
“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 a gift for a burnt offering to the LORD, whether to fulfill a vow or as a freewill offering, / You are not to present to the LORD any animal that is blind, injured, or maimed, or anything with a running sore, a festering rash, or a scab; you must not put any of these on the altar as an offering made by fire 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, for a special vow or freewill offering or appointed feast—