Sahih Muslim Book 6, Hadith Number 2457.

Chapter : Sexual Intercourse is completely forbidden during the day in the month of Ramadhan.

Abu Huraira (Allah be pleased with him) reported that a person came to the Apostle of Allah (may peace be upon him) and said: Messenger of Allah, I am undone. He (the Holy Prophet) said: What has brought about your ruin? He said: I have had intercourse with my wife during the month of Ramadan. Upon this he (the Holy prophet) said: Can you find a slave to set him free? He said: NO He (the Holy Prophet again) said: Can you observe fast for two consecutive months? He said: No. He (the Holy Prophet) said: Can you provide food to sixty poor people?, He said: No. He then sat down and (in the meanwhile) there was brought to the Apostle of Allah (may peace be upon him) a basket which contained dates. He (the Holy Prophet) said: Give these (dates) in charity. He (the man) said: Am I to give to one who is poorer than I? There is no family poorer than mine between the two lava plains of Medina. The Apostle of Allah (may peace be upon him) laughed so that his molar teeth became visible and said: Go and give it to your family to eat.