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. They also purified the gates and the wall with trumpets and the songs of psalms, with the people accompanying them by encircling. Together they purified with themselves the people, the gates, and the wall, offering great sacrifices after completing the circuit for the state of the citizens and the city. But also now, those who preside over the people with holy leadership, and have been taken by the Lord into spiritual ministry, carry with greater seriousness the memory of our dedication, which is in the future resurrection; thus, they strive the more earnestly to purify and sanctify both themselves and those entrusted to them; lest perhaps anyone, found in a defiled state of mind, be cast outside from the common joy of the holy solemnity and be bound hand and foot and cast into the outer darkness.
[AD 735] Bede on Nehemiah 12:30