פירוש על במדבר 18:11

תרומת מתנם [AND THIS IS THINE:] THE HEAVE OFFERING OF THEIR GIFTS (i.e. of offerings given of their free will) — that which is set apart from the thanksgiving offering (cf. Leviticus 7:34), and from the festival offerings and from the ram of the Nazarite (Numbers 6:17).

תרומת מתנם, what the owners of the animals in question give to the priests from the קדשים קלים, the offerings with a relatively lower level of sanctity, i.e. offerings in which the owners themselves have a share.

Which was set aside from the thanksgiving-offering. This refers to the breast, the thigh and one of the ten loaves that come with it. You might ask: What is Rashi’s source? Perhaps “terumah-gift” here refers to the gifts from produce. Therefore Rashi comments that afterwards it is written “of all the wave- offerings — since these require waving” such as the thanksgiving-offering, [the peace-offering] …