This is another major sin which people take with levity by merely seeing a person, they begin to slander him/her (due to his/her appearance or speech). Although the person is committing sins for not dressing properly or for foul speeches, yet it’s not permissible to slander him/her.
Allaah says (interpretation of the meaning):
“Verily, those who accuse chaste women, who never even think of anything touching their chastity and are good believers — are cursed in this life and in the Hereafter, and for them will be a great torment.” [al-Noor 24:23]
“Those who like that immorality (slander) should be spread (or publicize) among the Believers, will have a grievous Penalty in this life and in the Hereafter: Allah knows, and you know not.” [al-Noor, 24:19]
“And those who accuse chaste women, and produce not four witnesses, flog them with eighty stripes, and reject their testimony forever. They indeed are the Faasiqoon (liars, rebellious, disobedient to Allaah).” [al-Noor 24:4]
And the Prophet (peace and blessings of Allaah be upon him) said: “The best servants of Allah are those who, when they are seen, cause Allah to be remembered. The worst servants of Allah are those who go about slandering, who separate friends, and seek to distress the upright.” (Tirmidhi and Ahmad)
The scholars are unanimously agreed that it is obligatory to carry out the hadd punishment on one who slanders a chaste person, and the punishment is eighty lashes.
…May Allah give us a better understanding & guide us to accept the truth