Sahih Bukhari Volume 3, Book 31, Hadith Number 156.

Narated By ‘Aisha : A man came to the Prophet and said that he had been burnt (ruined). The Prophet asked him what was the matter. He replied, “I had sexual intercourse with my wife in Ramadan (while I was fasting).” Then a basket full of dates was brought to the Prophet and he asked, “Where is the burnt (ruined) man?” He replied, “I am present.” The Prophet told him to give that basket in charity (as expiation).