John Gill Commentary Nehemiah 4:21

"So we wrought in the work: and half of them held the spears from the rising of the morning till the stars appeared." — Nehemiah 4:21 (ASV)

So we laboured in the work
Of building the wall: and half of them held the spears; and other weapons before mentioned, (Nehemiah 4:16)

from the rising of the morning till the stars appeared ;
that is, from morning to evening, the space of time the builders and labourers worked.