Abu Hurairah (RAA) narrated that the Messenger of Allah (ﷺ) said:
"A sign of man's good observance of Islam (his piety) is to keep away from that which does not concern him." Related by At-Tirmidhi who graded it as Hadith Hasan. (DE)
English reference (DE): Book 16, Hadith 1518 (DE)
Arabic reference (DE): Book 16, Hadith 1475 (DE)