الأخلاق الذميمة
Abu Hurayrah (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "Beware of negative assumption, for negative assumption is the falsest of speech."
عن أبي هريرة -رضي الله عنه- عن النبي -صلى الله عليه وسلم-قال: «إيَّاكم والظنَّ, فإن الظنَّ أكذبُ الحديث».
شرح الحديث :
This Hadīth warns against negative assumption and suspicion that are not based on evidence, such that one relies on mere assumption and suspicion and judges accordingly. This is an evil moral, and it is the falsest of speech, because if the suspecting person relies on flimsy grounds, taking them as decisive premises for his conclusions, then his resulting statements are lies; rather, they are the most blatant lies.