דברי הימים א, פרק כ״ה, פסוק ח׳

The musical service in the Temple required careful organization to ensure both fairness and a continuous high standard of artistry. The musicians were divided into two distinct levels of proficiency. There were the master artisans, highly experienced experts in the wisdom of song [רש״י, מצודת דוד, ביאור שטיינזלץ], alongside the students, who had not yet perfected their craft and still required further instruction [רש״י, מצודת דוד, רלב״ג].

To organize these musicians into working groups, a lottery system was used. The primary approach among commentators is that this system established absolute equality among all participants. The lottery determined the order of service, specifically establishing who would play the instruments first [מצודת דוד]. A master's advanced skill did not grant him any priority. Whoever was drawn first, whether a young student or an older expert, won the right to serve in the first shift, with the rest following in sequence [רש״י, מצודת דוד]. These Levite musical shifts were set up to correspond directly with the shifts of the Priests. Each Levite group stood opposite and served in parallel to a specific Priestly group, directly determined by the order of the lottery [רש״י, מצודת ציון].

While this perspective views the lottery primarily as a way to determine the sequence of service, another approach suggests the drawing was designed to create internal balance within the groups themselves. The singers were divided into twenty-four distinct shifts, with twelve men assigned to each [רלב״ג]. According to this view, the division intentionally mixed experts and students together in every single group. This guaranteed that every shift maintained the exact same high quality of music. The master musicians would lead the singing, while the students sang alongside them, gaining practical experience and learning directly from their mentors [מלבי״ם].