Sahih Bukhari
Good Manners and Form (Al-Adab)
Volume: 008 / Book Number: 073 / Hadith Number: 83
Narrated Abu Huraira:
The Prophet said, "Whoever does not give up false statements (i.e. telling lies), and evil deeds, and speaking bad words to others, Allah is not in need of his (fasting) leaving his food and drink."