Allah, the Exalted, says:

"O you who believe! Avoid much suspicions, indeed some suspicions are sins.'' (49:12)

1573. Abu Hurairah (May Allah be pleased with him) said: The Messenger of Allah (PBUH) said, "Beware of suspicion, for suspicion is the worst of false tales.''
[Al-Bukhari and Muslim].

Commentary: This Hadith has already been mentioned (No. 15). It warns us against suspicions about other Muslims as this involves telling lies about them, which is strictly forbidden. This is the reason why it is referred to as the worst of false tales. We also learn from this Hadith that the orders and punishments of Shari`ah are enforced on certainty, not on speculations and conjectures.