Hadith: Do not seek faults

Abu Barzah al-Aslami reported: The Messenger of Allah, peace and blessings be upon him, said, “O you who have faith with their tongues but faith has not entered their hearts! Do not backbite the Muslims or seek their faults. Whoever seeks their faults, Allah will seek his faults. And if Allah seeks his faults, He will expose him even in the privacy of his own house.”

Source: Sunan Abī Dāwūd 4880

Mu’awiyah reported: The Messenger of Allah, peace and blessings be upon him, said, “Verily, if you seek out the faults of people, you will corrupt them or nearly corrupt them.”

Source: Sunan Abī Dāwūd 4888

Hadith: Faults of others

"Thinking about things that one shouldn't be thinking about is considered prohibited. Including that would be weaknesses/faults of Muslims whether they be absent or present. A hadith: there's a tree in paradise for the one whose preoccupation with his OWN faults causes him to forget the faults of others. Everybody's got faults & if you start thinking about other peoples' faults, you're just a fool." - Hamza Yusuf