Ensuring the economic stability of public servants is an essential requirement for them to carry out their spiritual and practical duties. The king issues an order to the residents of Jerusalem, a population that included people from Judah and Benjamin as well as refugees from Ephraim and Manasseh, to provide the holy servants with their rightful dues. This mandate requires giving the priests and Levites the agricultural gifts required by the Torah, such as the uplifted offering, the first tithe, dough offerings, and first fruits [מצודת דוד, רלב״ג, ביאור שטיינזלץ]. By fulfilling this duty, the people allow their spiritual leaders to fully commit to their calling.
The primary approach among commentators is that the central purpose of these gifts is to free the priests and Levites from the daily stress of earning a living. Once their financial needs are securely met, they have the peace of mind to focus completely on their Temple duties, studying the Torah, and teaching it to the nation [רש״י, מצודת דוד, רלב״ג, ביאור שטיינזלץ]. In fact, the full depth of the Torah is meant to be studied by those whose income arrives without heavy labor. This mirrors the generation that wandered in the desert and was sustained by manna, setting a precedent for the priests who are sustained by holy offerings [רש״י].
From a practical standpoint, the people may have already been separating these agricultural gifts. However, the priests and Levites previously had to travel across the land from one threshing floor to another just to collect their portions. This constant travel drained their time and hurt their ability to properly study. The new instruction requires the people to bring the gifts directly to the spiritual leaders, clearing their schedules entirely for deep study and service [רלב״ג].
Alternatively, another perspective views this command not just as a practical fix to enable study, but as a strict condition regarding who actually receives the support. According to this approach, the people are instructed to give their tithes and offerings only to those priests and Levites who actively engage in studying the Torah, withholding them from anyone who neglects their spiritual responsibilities [מלבי״ם].