#23 Foul speech
Book of Fasting
(8) Chapter: Whoever does not give up lying speech while observing Saum
Sahih al-Bukhari 1903
Narrated Abu Huraira:
The Prophet (صلى الله عليه و سلم) said, “Whoever does not give up forged speech and evil actions, Allah is not in need of his leaving his food and drink (i.e. Allah will not accept his fasting.)”