Hadith 4:18
Hashim narrated to us, he said: Mujalid informed us, from al-Sha'bi, from Ali, that fasting is not [merely abstaining] from food and drink, but [it is also abstaining] from lying, falsehood, and vain talk.
حدثنا هشيم قال انا مجالد عن الشعبي عن علي ان الصيام ليس من الطعام والشراب ولكن من الكذب والباطل واللغو