An ambitious young man told his pastor he'd promised God a tithe of his income. They prayed for God to bless his career. At that time he was making $40.00 per week and tithing $4.00. In a few years his income increased and he was tithing $500.00 per week. He called on the pastor to see if he could be released from his tithing promise, it was too costly now. The pastor replied, "I don't see how you can be released from your promise, but we can ask God to reduce your income to $40.00 a week, then you'd have no problem tithing $4.00."
A Guidebook for Pastors, by W. A. Criswell