Strong H5071 נְדָבָה nedâbâh · voluntariness

Numbers

1. Numbers 15:3
   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 savour unto the Lord, of the herd, or of the flock:
2. Numbers 29:39
   These things ye shall do unto the Lord in your set feasts, beside your vows, and your freewill offerings, for your burnt offerings, and for your meat offerings, and for your drink offerings, and for your peace offerings.