Bede

And the priests and Levites purified themselves, etc. It is a wholly just order that those teachers and prelates who wish to purify the people should first be purified themselves; first, they should chastise their own body and bring it into servitude, lest perhaps, while preaching to others, they themselves should be found reprobate (I Cor. IX). The priests and Levites were purified by prayers and by the offerings of sacrifices, and also by abstaining from wives, they purified the people by preaching the same continence. …

Commentary on Ezra and Nehemiah ↗