The Prophet (peace and blessings of Allaah be upon him) said:
“When any of you is fasting, let him not commit sin…” [Reported by al-Bukhaari, al-Fath, no. 1904]
“Whoever does not stop speaking falsehood and acting in accordance with it, Allaah has no need of him giving up his food and drink.” [Al-Bukhaari, al-Fath, no. 1903]