The Messenger of Allah ﷺ said, "Beware of suspicion, for suspicion is the most false form of speech. Do not spy on one another, and do not seek out one another's faults."
حدثنا عبد الله بن مسلمة عن مالك عن أبي الزناد عن الأعرج
أن رسول الله ﷺ قال إياكم والظن فإن الظن أكذب الحديث ولا تحسسوا ولا تجسسوا
Takhrij (source references): Bukhari narrated it in the Book of Manners, Chapter "O you who believe, avoid much suspicion..." etc., hadith no. 6066, and Muslim in the Book of Righteousness and Kinship Ties, Chapter on the Prohibition of Suspicion, Spying, Rivalry, Outbidding One Another and the Like, hadith no. 2563, both from the hadith of Malik through this same chain. It is also found in Muwatta (Yahya's recension), 2/907, 908.