במדבר, פרק י״ח, פסוק כ״ט

Receiving gifts brings a responsibility to give back. The Levites are instructed to set aside a dedicated portion for God from the tithes they receive. This obligation covers all gifts granted to them by the Israelites [שטיינזלץ], as well as the produce grown in the fields of the Levitical cities, since those lands were also given to them as a gift [חזקוני, מלבי״ם]. It even extends to extra produce an Israelite might give a Levite beyond the strict requirements of the law [העמק דבר]. Additionally, a specific rule emerges regarding the sequence of giving. If a person happens to separate this required portion before setting aside the first fruits, the action remains valid [תורה תמימה].

The primary approach among commentators focuses on a unique legal scenario regarding the order in which these portions are taken. Normally, an Israelite first gives the primary priestly portion, then gives the first tithe to the Levite, who in turn gives a tithe of that tithe to the priest. However, a situation can arise where the Levite takes his tithe directly from the processed grain pile before the Israelite has separated the initial priestly portion. In this case, the Levite assumes the responsibility to separate both the primary priestly portion, typically one out of fifty, and his own required tithe from what he collected. This dual obligation only applies if the Levite took the grain after it was fully processed. If he collected it while it was still unprocessed on the stalks, he is exempt from the primary priestly portion and only needs to separate his standard tithe.

When setting aside this dedicated share, the Levite must choose from the absolute best, most beautiful, and cleanest part of the yield [אבן עזרא, חזקוני, רלב״ג, ביאור יש״ר, שטיינזלץ]. Consequently, one cannot separate inferior produce to fulfill the obligation for superior produce [רש ר הירש, תורה תמימה]. If an Israelite gives a Levite a tithe consisting entirely of premium quality fruits, the Levite cannot claim that the Israelite intended this exceptional quality solely for his personal benefit. Instead, he must give the priest's share from that exact same premium batch [העמק דבר]. There is a leniency allowing one to separate a portion from ritually pure fruits to cover ritually impure ones [תורה תמימה, מלבי״ם].

Before the required portion is separated, its latent sanctity rests within the entire crop, forbidding anyone from using the produce until the holy share is removed [רלב״ג, ביאור יש״ר, שטיינזלץ, אבן עזרא]. When taking the primary priestly portion, the produce used must be physically close to the crop it exempts, whereas the Levite's tithe can be separated even from produce that is not in the immediate vicinity [תורה תמימה]. Finally, these laws establish the rules for accidental mixtures. If one part of a holy portion falls into one hundred parts of regular produce, the entire mixture becomes forbidden to non-priests. The holy portion is only nullified, making the mixture permissible to eat, if there are exactly one hundred and one parts of regular produce to offset it [תורה תמימה, רש ר הירש, מלבי״ם].