Donald S. Whitney, Spiritual Disciplines for the Christian Life, 1991, p. 143.
The proportion of your income that you give back to God is one distinct indication of how much you trust Him to provide for your needs… We will give to the extent that we believe God will provide for us. The more we believe God will provide for our needs, the more we are willing to risk giving to Him. And the less we trust God, the less we will give to Him.
Donald S. Whitney, Spiritual Disciplines for the Christian Life, 1991, p. 143.