Matthew Henry Commentary Nehemiah 7:1-4

"Now it came to pass, when the wall was built, and I had set up the doors, and the porters and the singers and the Levites were appointed, that I gave my brother Hanani, and Hananiah the governor of the castle, charge over Jerusalem; for he was a faithful man, and feared God above many. And I said unto them, Let not the gates of Jerusalem be opened until the sun be hot; and while they stand [on guard], let them shut the doors, and bar ye them: and appoint watches of the inhabitants of Jerusalem, every one in his watch, and every one [to be] over against his house. Now the city was wide and large; but the people were few therein, and the houses were not builded." — Nehemiah 7:1-4 (ASV)

Nehemiah, having finished the wall, returned to the Persian court, and came to Jerusalem again with a new commission. The public safety depends on everyone's care to guard himself and his family against sin.