An-Nawawi Hadith - 12

مِنْ حُسْنِ إِسْلاَمِ الْمَرْءِ تَرْكُهُ مَا لاَ يَعْنِيهِ حَدِيثٌ حَسَنٌ، رَوَاهُ التِّرْمِذِيُّ وَغَيْرَهُ هكَذَا

On the authority of Abu Hurairah, radiyallahu 'anhu, who said : The Messenger of Allah, sallallahu 'alayhi wasallam, said: "Part of the perfection of someone's Islam is his leaving alone that which does not concern him." [Hadith hasan - Recorded by Tirmidhi]