Hadith about Requirements of Enjoining Good and Forbidding Evil

"We have been prohibited from spying (on Muslims) and finding faults (with them). But we can take to task only and only if the sin is overt. [Abu Dawud].

وعن ابن مسعود رضي الله عنه أنه أتي برجل فقيل له، هذا فلان تقطر لحيته خمرًا، فقال‏:‏ إنَّا قد نهينا عن التجسس، ولكن إن يظهر لنا شئ، نأخذ به‏"‏‏.‏ حديث حسن صحيح رواه أبو داود بإسناد على شرط البخاري ومسلم‏.‏

Narrated by Abdullah ibn Mas‘ūd + 1 other version

I implore you by Allah (to tell me) if you heard the Messenger of Allah (may Allah's peace and blessings be upon him) saying: Answer on my behalf. O Allah, aid him with the Holy Spirit. He said: By Allah, yes

Abu Hurayrah reported that ‘Umar happened to pass by Hassān (may Allah be pleased with him) as he was reciting verses of poetry in the mosque. He (‘Umar) looked at him (meaningfully). Upon which, Hassān said: "I used to recite poetry (in the presence) of one better than you (the Prophet). He then…

عُمَرَ، مَرَّ بِحَسَّانَ وَهُوَ يُنْشِدُ الشِّعْرَ فِي الْمَسْجِدِ فَلَحَظَ إِلَيْهِ فَقَالَ قَدْ كُنْتُ أُنْشِدُ وَفِيهِ مَنْ هُوَ خَيْرٌ مِنْكَ ‏.‏ ثُمَّ الْتَفَتَ إِلَى أَبِي هُرَيْرَةَ فَقَالَ أَنْشُدُكَ اللَّهَ…

Narrated by Hassān ibn Thābit Explained