דברי הימים א, פרק כ״ג, פסוק י״ג

Within the broader structure of the holy tribe of Levi, a distinct separation of duties took place to elevate one specific lineage to the highest level of sanctity. The family of Amram was divided into two separate branches. Even though the entire Levite tribe, including the Kohath family, was already dedicated to a holy purpose, Aaron and his descendants were set apart to achieve a supreme degree of holiness. As a result of this division, Moses remained counted among the regular members of the Levite tribe, while Aaron was completely separated to serve as a priest [מלבי״ם, רלב״ג, ביאור שטיינזלץ].

The responsibilities entrusted to Aaron and his sons involved highly specific acts of divine service. They were tasked with offering incense and serving God, which refers to the sacred duties reserved exclusively for the priests, such as performing the service on the altar and working inside the sanctuary [ביאור שטיינזלץ]. Additionally, they were given the role of blessing the people in His name. This is understood as the commandment of the Priestly Blessing, a sacred act the priests fulfill by raising their hands [מצודת דוד, רלב״ג].