Q: What is the significance and the ruling if the sunnah about "loving fellow believers and not taunting them" according to some Ahaadith like this:
Sayyiduna Mu’adh (radiyallahu ‘anhu) narrates that Muhammad (sallallahu ‘alayhi wasallam) said: ‘Whoever taunts a brother (Muslim) with a sin (which the Muslim has committed), will not die until he (the taunter) commits the same sin.’
The first Hadith is recorded by Imam Tirmidhi (rahimahullah) in his Sunan and is classified as sound (hasan). (Sunan Tirmidhi, Hadith: 2505 & Mukhtasarul Maqasidil Hasanah, Hadith: 1057. Also see: Targhib, vol.3 pg.310, Sharhul Ihya, vol.7 pg.504 & Al-Mudawi, Hadith: 3462)