God says:
And [remember] Job, when he cried out to his Sustainer, “Affliction has befallen me: but Thou art the most merciful of the merciful!” * – whereupon We responded unto him and removed all the affliction from which he suffered; and We gave him new offspring, doubling their number as an act of grace from Us, and as a reminder unto all who worship Us.-- Q.21: 83-84
The story of Job (Ayyub in Arabic), describing his erstwhile happiness and prosperity, his subsequent trials and tribulations, the loss of all his children and his property, his own loathsome illness and utter despair and, finally, God’s reward of his patience in adversity, is given in full in the Old Testament (The Book of Job). This Biblical, highly philosophical epic is most probably a Hebrew translation or paraphrase – still evident in the language employed – of an ancient Nabataean (i.e., North-Arabian) poem, for > > * “Job, the author of the finest piece of poetry that the ancient Semitic world produced, was an Arab, not a Jew, as the form of his name (Iyyob) and the scene of his book, North Arabia, indicate” (Philip K. Hitti, History of the Arabs, London 1937, pp.42-43). Since God “spoke” to him, Job ranks in the Qur’an among the prophets, personifying the supreme virtue of patience in adversity: (sabr).
[Abraham in his sermon to his people said:] and when I fall ill, (He) is the One who restores me to health -- Q26: 80
Nay – who it is that responds to the distressed when he calls out to Him, and who removes the ill [that caused the distress], … Q.27: 62
Prophet said
1. “When you visit the sick, remove his anxiety about his death. (Though) it cannot avert anything but it would comfort his soul’ – H: Ibn Majah. N: Abu Sa’yeed.
2. “When you visit the sick, ask him to pray for you. His prayer ranks same as the prayer of the angels” – H: Ibn Majah. N: Omer-b-alKhattab.
3. “When a Muslim visits his brother Muslim in sickness, he certainly continues to pluck fruits of paradise till he returns” – H: Muslim. N: Saoban.
4. Bibi Ayesha reported: When anyone complained of his illness to the Messenger of God, he used to pass his right hand over him and then say: “Take away the trouble, O lord of mankind, and heal O thou Healer! There is no cure except Thy cure – a cure that does not leave any ailment” – H: Bukhari and Muslim.
5. Bara`a-b-‘Azeb reported: A man complained to the Prophet of being usually depressed and restless and said he had no peace of mind. The Prophet advised him to recite much: “SUBHANAL MALIKAL QUDDOOS, RABBUL MALAIKATI WARROOH, JALALATAS SAMAWATI WAL ARD BIL ‘IZZATI WAL JABROOT.” He got completely cured of his ills and peace of mind returned to him. – H: Majma-ul-zawa’ed wa Makhzanul Fawa’ed.
Nursing and visiting the sick is “sunnat” in cases of general sickness when there is no risk to life. On the other hand it is ‘Farz kefayah’ (compulsory for the community as a whole) in case lack of attention endangers life of the sick. If one Muslim looks after the patient, the whole community is absolved of the responsibility, failing which the entire body of Muslims will be responsible. – (Al-Hadis, sec. 3 pg.281. Vol. 1. Quoting Ghazali`s ‘Ihya’.)