John Gill's  Exposition of the Bible 

1 Chronicles 29:6

Then the chief of the fathers and princes of the tribes of Israel, and the captains of thousands and of hundreds, with the rulers of the king's work, offered willingly,

Then the chief of the fathers and princes of the tribes of Israel,.... The princes of the twelve tribes:

and the captains of thousands, and of hundreds, with the rulers over the king's work; who were now assembled, 1 Chronicles 28:1

offered willingly; and cheerfully; needed no more arguments to press them to it, but at once readily communicated.