All perfect praise be to Allah, The Lord of The Worlds. May His peace and blessings be upon our Prophet Muhammad and upon all his family and companions.
It is prohibited to mock or degrade any human being in general and those afflicted with disease in particular. It is also prohibited to mock the people of a country or a region smitten with a disease or an affliction. The evidence on this is that Allah, The Exalted, said (What means): O ye who believe! Let not a folk deride a folk who may be better than they (are), not let women (deride) women who may be better than they are; neither defame one another, nor insult one another by nicknames. Bad is the name of lewdness after faith. And whoso turneth not in repentance, such are evil-doers.” {al-Hujurat/11}.
Moreover, the Islamic moral code commands a Muslim to respect people and their status and show appreciation to fellow humans because dignity is a common platform for all. This is attested to in the verse where Allah, The Exalted, said {What means}:" Verily we have honored the Children of Adam. We carry them on the land and the sea, and have made provision of good things for them, and have preferred them above many of those whom We created with a marked preferment.” {Al-Isra’/70}.
Besides, a Muslim knows that sickness and disease come from Allah and that He afflicts whoever He chooses for a hidden wisdom or purpose. Further, Al-Imam Al-Bukhari reported:" Which of the people is tried most severely?" He said: "The Prophets, then those nearest to them. Moreover, narrated `Abdullah: I visited the Prophet (PBUH) during his illness and touched him while he was having a fever. I said to him, "You have a high fever; is it because you will get a double reward?" He said, yes. No Muslim is afflicted with any harm, but that his sins will be annulled as the leave of a tree fall down." {Al-Bukhari}.
The Prophet (PBUH) forbade expressing pleasure at the misfortune of a Muslim brother where he said (What means):" Do not express pleasure at the misfortune of a (Muslim) brother lest Allah should bestow mercy upon him and make you suffer from a misfortune."{Tirmithi}. This is because expressing pleasure at people’s misfortune contradicts with the teachings of Islam.
Furthermore, at times of affliction, a Muslim should always seek the pleasure of Allah and draw closer to Him through supplication, prayer, remembrance, good deeds, charities, avoiding sin, asking Allah for pardon and Al-Afiyah to him and to all people, because Abu Bakr stood upon the Minbar, then wept, and said: ‘The Messenger of Allah (PBUH) stood upon the Minbar the first year (of Hijrah), then wept, and said: “Ask Allah for pardon and Al-`Āfiyah, for verily, none has been given anything better than Al-`Āfiyah.’” {At-Tirmithi}.
Therefore, whoever committed this sin must repent to Allah, ask for His forgiveness and ask pardon from the people whom he had mocked, but if he couldn’t do so, then he should persist on invoking Allah on their behalf in order to be forgiven since Allah is the Forgiver of sins. And Allah knows best.