Sahih Muslim Book 5, Hadith Number 2244.

Chapter : Exhortation to give charity even though it is small; (the one who gives) small amount should neither be discouraged not looked down upon.

Asma’ reported Allah’s Messenger (way peace be upon him) as saying (to her): Spend and do not calculate, (for) Allah would calculate in your case; and do not hoard, otherwise Allah would be withholding from you.