Hadis

On the authority of Al-Hasan bin Ali, the grandson of the messenger of Allah, who said : I memorized from the messenger of Allah his saying : "Leave that which makes you doubt for that which does not make you doubt."
Narrated by Tirmizi and Nasaee, and Tirmizi said it is true and fine hadis.

On the authority of Abu Hurairah, who said : The messenger of Allah said : "Part of someone's being a good Muslim is his leaving alone that which does not concern him."
fine hadis narrated by Tirmizi and others.

On the authority of Anas bin Malik, the servant of the messenger of Allah that the prophet said: "None of you [truely] believes until he wishes for his brother what he wishes for himself."
Related by Bukhari and Muslim