“The Messenger of Allah (Allah bless him and give him peace) said,
“From the excellence of a man’s Islam is leaving that which does not concern him.”
“That is, to leave that which is not important or befitting of him, whether in speech, actions, or thought.
Thus, ‘the excellence of a man’s Islam’ is its perfection, such that one remains steadfast in the submission to the commands and prohibitions of Allah, and surrenders to His rulings in accordance to His destiny and decree (qada wa qadr). This is the sign of the heart having been expanded by the light of its Lord, and the descent of quietude (sakina) into the heart. The reality of ‘that which does not concern him’ is that which is not needed for a worldly or next-worldly necessity, and does not aid in attaining his Lord’s good pleasure, such that it is possible to live without it…
This includes excess acts and unnecessary speech… This hadith may well be taken from Allah Most High’s saying,
“And who shun all vain things.” (Qur’an, 23: 3)
Mulla Ali al-Qari (Allah have mercy on him) mentioned this in his commentary on Mishkat al-Masabih.