Nehemiah 13:22, 30-31

Then I directed the Levites to ceremonially cleanse themselves and take over as guards at the gates to keep the sanctity of the Sabbath day. Remember me also for this, my God. Treat me with mercy according to your great and steadfast love. * * *

All in all I cleansed them from everything foreign. I organized the orders of service for the priests and Levites so that each man knew his job. I arranged for a regular supply of altar wood at the appointed times and for the firstfruits. Remember me, O my God, for good.