律戒本疏 1.52

1.52

半月說戒　半月不說戒突。說則清淨。亦能淨眾俱意犯得悔除故。又三默然。令犯者思愆。眾無疑悔故也。

Reciting the precepts every half-month.
Not reciting the precepts every half-month is a duṣkṛta. Reciting brings purity, and it can also purify the assembly, because offenses committed by common intention can be repented and eradicated. Furthermore, the three silences cause offenders to reflect upon their faults, so that the assembly has no doubt or regret.