Matthew Henry on 1 Chronicles 29:1-9

What is done in works of piety and charity, should be done willingly, not by constraint; for God loves a cheerful giver. David set a good example. This David offered, not from constraint, or for show; but because he had set his affection to the house of God, and thought he could never do enough towards promoting that good work. Those who would draw others to good, must lead the way themselves.