Nehemiah 13:22

And I commanded the Levites that they should cleanse
themselves
From all ceremonial uncleanness, that they might be fit in a ceremonial sense to perform the duties of the office on the sabbath day:

and that they should come and keep the gates, to sanctify the
sabbath day;
not the gates of the city, his servants were placed there, nor was this the work of the Levites, and much less did this require a particular purification to fit for it; but the gates of the temple, that no impure person might enter there; and on that day it required the greater diligence, because of the number of people that came to worship:

remember me, O my God, concerning this also;
with respect to his care to have the sabbath kept holy, as well as his concern for the honour of the house of God, and the maintenance of his ministers, ( Nehemiah 13:14 ) ,

and spare me according to the greatness of thy mercy;
he desired to be dealt with, not according to any merits of his own, but according to the abundant mercy of God; that he would kindly and graciously vouchsafe to accept any good that he had done for his mercy sake, and forgive whatever was amiss in him.