Аль-Хумаза 104:1

Warning against dreadful end of those committing three obnoxious sins

This Surah warns of the severe punishment on three grave sins, and then highlights the nature of that severe punishment. The three sins are backbiting, deriding and selfish hoarding of wealth. The words hamz and lamz are used in several senses. Most commentators agree that the word hamz, from which is derived the word humazah, means to 'backbite', that is, to speak ill of a person behind his back. The word lamz, from which is derived the word lumazah, means to 'slander' or 'to deride', that is, to speak ill of a person to his face. Both these sins are morally and socially obnoxious and deadly. The Qur'an and the Sunnah have sounded a stern warning against these sins. However, 'backbiting' is, from one perspective, worse than 'slander'. 'Backbiting' is worse because the ill of a person is spoken behind his back; the victim is not present to defend himself and put an end to it; thus the sin continues to be committed to a greater and increasing degree. 'Slander', on the other hand, though an obnoxious sin in itself, is relatively less in degree than backbiting, because the victim is present to defend himself and put an end to face-to-face insulting or fault-finding with him. From another perspective 'slander' is worse than 'backbiting', because to speak ill of a person to his face is tantamount to insulting him and denigrating him. This is morally and socially more harmful and hurting, and therefore its punishment is more dreadful. According to a Hadith, the Holy Prophet ﷺ has said,

شِرارُ عِبَادِ اللہِ تَعَالٰی المَشَّاءُونَ بِالنَّمِیمَۃِ المُفَرِّقُونَ بَینَ الاَحبَّۃِ البَاعُونَ البُرَآَءَ العنت

"The worst servants of Allah are those who speak ill of someone, creating enmity between friends and finding fault with innocent people."