The Prophet (صلى الله عليه وسلم) said:
Whoever does not abandon false speech, acting according to it and ignorance, then Allah has no need of him abandoning his food and drink”
Al-Bukhari no 1903
Sulaymân b. Mûsâ [d119H] – Allah have mercy on him – said:
When you fast, your hearing and sight should also fast, and your tongue should fast by keeping away from lies; and do not harm your servant. Don’t let the day you fast be the same as the day you don’t fast.
Târîkh Dimishq Vol. 22 p389.