It is narrated from Hazrat Abu Hurairah (may Allah be pleased with him) that once the Noble Prophet (peace and blessings be upon him) encouraged the people to give charity. A man said, "What if I have only one dinar?" He replied, "Give it in charity to yourself." He asked, "What if I have one more dinar?" He replied, "Give it in charity to your wife." He asked, "What if I have one more dinar?" He replied, "Give it in charity to your child." He asked, "What if I have one more dinar?" He replied, "Give it in charity to your servant." He asked, "What if I have one more dinar?" He replied, "You know best."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 10086