John Gill Commentary Nehemiah 3:14

"And the dung gate repaired Malchijah the son of Rechab, the ruler of the district of Beth-haccherem; he built it, and set up the doors thereof, the bolts thereof, and the bars thereof." — Nehemiah 3:14 (ASV)

But the dung gate repaired Malchiah the son of Rechab
If this was one of the Rechabites, they were forbid to build houses, (Jeremiah 35:7) but, perhaps, though they might not build private houses for themselves to dwell in, they might be employed in building walls and fortresses for public security; though it is more probable that this man was not of that family:

the ruler of part of Bethhaccerem ;
or of the tract of Bethhaccerem, a place between Tekoah and Jerusalem; see (Jeremiah 6:1) ,

he built it, and set up the doors thereof ;
&c. as in (Nehemiah 3:3) .