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. (Numbers 29:39)
In addition to all these regularly prescribed sacrifices, an individual might offer an additional burnt offering, either as a mark of gratitude to Jehovah or in performance of some vow.
These things ye shall do.
The Lord had appointed certain festivals for certain seasons. These were to be carried out in the precise manner He had prescribed.
Burnt offerings.
Compare Lev. 22:18-21; Num. 15:1-13. The sacrifices of this chapter were enjoined above and beyond all burnt offerings, meat offerings, drink offerings, and peace offerings presented in fulfillment of special vows.