Speak unto the children of Israel, and say unto them, If any man of you bring an offering unto the Lord, ye shall bring your offering of the cattle, even of the herd, and of the flock. 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. ~ Leviticus 1:2-3

I will freely sacrifice unto thee: I will praise thy name, O Lord; for it is good. ~ Psalm 54:6

Speak unto Aaron, and to his sons, and unto all the children of Israel, and say unto them, Whatsoever he be of the house of Israel, or of the strangers in Israel, that will offer his oblation for all his vows, and for all his freewill offerings, which they will offer unto the Lord for a burnt offering… ~ Leviticus 22:18

Speak unto the children of Israel, and say unto them, when ye be come into the land of your habitations, which I give unto you, and will make an offering by fire unto the Lord, a burnt offering, or a sacrifice in performing a vow, or in a freewill offering, or in your solemn feasts, to make a sweet savoir unto the Lord, of the herd or of the flock… ~ Numbers 15:2-3

And afterward offered the continual burnt offering, both of the new moons, and of all the set feasts of the Lord that were consecrated, and of every one that willingly offered a freewill offering. ~ Ezra 3:5

And all the silver and gold that thou canst find in all the province of Babylon, with the freewill offering of the people, and of the priests, offering willingly for the house of their God which is in Jerusalem… ~ Ezra 7:16