דברי הימים א, פרק כ״ה, פסוק י׳

The musical arrangement in the Temple relied on an organized system of fixed groups working in rotating shifts. Through a lottery used to assign these roles, the third rotation fell to Zaccur, the eldest son of Asaph [רש״י].

Like the other groups in this system, Zaccur's shift was made up of exactly twelve men, consisting of his sons and brothers. This specific arrangement highlights a structured working environment where each unit functioned as a family team. Every group of twelve was composed entirely of relatives who were also highly skilled musicians [שטיינזלץ].