Albert Barnes Commentary Nehemiah 13:22

"And I commanded the Levites that they should purify themselves, and that they should come and keep the gates, to sanctify the sabbath day. Remember unto me, O my God, this also, and spare me according to the greatness of thy lovingkindness." — Nehemiah 13:22 (ASV)

I commanded the Levites - At first Nehemiah had employed his own retinue (Nehemiah 13:19) in the work of keeping the gates. He now assigned the duty to the Levites, as one which properly belonged to them, since the object of the regulation was the due observance of the Sabbath.