What is "Reishis ha'Cherem"?
Rashi: It is the best of the Cherem. This is like "Reishis Deganecha" (Devarim 18:4), which should be the best - "b'Harimchem Es Chelbo Mimenu 1 " (Bamidbar 18:30). Malbim - it is proper that Reishis ha'Cherem go to Otzar Hashem!
Rashi citing Targum Yonasan: [The people separated animals from the spoils] before they were made Cherem. Radak - this was to offer to Hashem, not for anything else!
Radak: We learn from "Reishis Shemanim Yimshechu" (Amos 6:6). (This is a better source, for perhaps Reishis Deganecha teaches only that one must separate Terumah before eating; we learn to take highest quality from "Chelbo". I did not find anyone discuss whether l'Chatchilah one may take intermediate produce for Terumah. - PF)
