كَفَى بِالْمَرْءِ كَذِبًا أَنْ يُحَدِّثَ بِكُلِّ مَا سَمِعَ
It is enough falsehood for a person to relate everything they hear.
Source: مسلم
كَفَى means “is sufficient,” بِالْمَرْءِ refers to a person, كَذِبًا indicates falsehood, and يُحَدِّثَ means “to relate.” Passing on every rumor can circulate falsehood, since not everything heard is accurate.
كَفَى is a past-form verb used in this expression; كَذِبًا is a specification (tamyīz) clarifying “sufficient in what respect?” The present verb يُحَدِّثَ follows أَنْ, while سَمِعَ is the past verb “heard.”