Verse 21. - So we laboured: and half of them held the spears. This is a summary of the main points previously related: "So we continued to work; and one-half of my personal followers continued to keep watch, and to hold the spears" (ver. 16). From the rising of the morning, etc. This is additional, and shows how early the work commenced each morning, and how late it continued.
4:16-23 We must watch always against spiritual enemies, and not expect that our warfare will be over till our work is ended. The word of God is the sword of the Spirit, which we ought to have always at hand, and never to have to seek for it, either in our labours, or in our conflicts, as Christians. Every true Christian is both a labourer and a soldier, working with one hand, and fighting with the other. Good work is likely to go on with success, when those who labour in it, make a business of it. And Satan fears to assault the watchful Christian; or, if attacked, the Lord fights for him. Thus must we wait to the close of life, never putting off our armour till our work and warfare are ended; then we shall be welcomed to the rest and joy of our Lord.
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.