Nehemiah 13:22; Nehemiah 13:30

22 And I commanded the Levites that they should purify themselves and come as gatekeepers to sanctify the sabbath day. For this also remember me, O my God, and have compassion on me according to the greatness of Your lovingkindness.

30 Thus I purified them from everything foreign and appointed duties for the priests and the Levites, each in his task,