'Willingly' in the Bible

Then the rulers of the fathers’ households, and the princes of the tribes of Israel, and the commanders of thousands and of hundreds, with the overseers over the king’s work, offered willingly;

Then the people rejoiced because they had offered so willingly, for they made their offering to the Lord with a whole heart, and King David also rejoiced greatly.

Since I know, O my God, that You try the heart and delight in uprightness, I, in the integrity of my heart, have willingly offered all these things; so now with joy I have seen Your people, who are present here, make their offerings willingly to You.