Exodus 29:28

²⁸ and it shall be for Aaron and his sons as their portion forever from the children of Israel; for it is a wave offering: and it shall be a wave offering from the children of Israel of the sacrifices of their peace offerings, even their wave offering to Yahweh.

Two and a half

In Exodus 25:10, this signifies much and full; when predicated of the Divine it signifies all. Its meaning is similar to that of five and ten.