'Prescribed' in the Bible

Aaron's sons Nadab and Abihu each took his own censer, placed fire in it, covered it with incense, and brought it into the LORD's presence as unauthorized fire that he had never prescribed for them.

Eat at a sacred place, because it's your and your sons' prescribed portions. It's from the offering made by fire to the LORD, since I've commanded it.

As to the breast and thigh raised offerings, you and your sons and daughters with you may eat them at a clean place, because they belong to you and are your sons' prescribed portions and were taken from the sacrifices of peace offering presented by the Israelis.