2 Corinthians 8:3-4
For I can testify that to the utmost of their power, and even beyond their power, they have of their own free will given help.
2 Corinthians 8:12
For, assuming the earnest willingness, the gift is acceptable according to whatever a man has, and not according to what he has not.
2 Corinthians 8:17
for Titus welcomed our request, and, being thoroughly in earnest, comes to you of his own free will.
2 Corinthians 9:5
I have thought it absolutely necessary therefore to request these brethren to visit you before I myself come, and to make sure beforehand that the gift of love which you have already promised may be ready as a gift of love, and may not seem to have been something which I have extorted from you.