John Wesley on Nehemiah 13:22

Cleanse - Because the work they now were set upon, though common in its nature, yet was holy in design of it, and had respect unto the sabbath: and, because the day in which they were to do this was the sabbath - day, for the observation whereof they were obliged to purify themselves. Gates - The gates of the city; not daring to trust the common porters, he commits the charge of them upon the sabbath - days, to the Levites, to whom the care of sanctifying the sabbath did properly belong. Mercy - Whereby he intimates, that though he mentioned his good - works, as things wherewith God was well - pleased, and which he had promised to reward, yet he neither did, nor durst trust to their merit, or his own worthiness, but, when he had done all, he judged himself an unprofitable servant, and one that needed God's infinite mercy to pardon all his sins, and particularly those infirmities and corruptions which adhered to his good deeds.