Visiting the sick is called ‘iyaadah in Arabic (from a root word meaning return) because people come back time after time.
Ruling on visiting the sick
Some of the scholars are of the view that it is a confirmed Sunnah (Sunnah mu’akkadah). Shaykh al-Islam (Ibn Taymiyah) favoured the view that it is a communal obligation (fard kifaayah), as stated in al-Ikhtiyaaraat (p. 85) and this is the correct
view. It is proven in al-Saheehaayn that the Prophet (peace and blessings of Allaah be upon him) said: “There are five duties that the Muslim owes to his brother Muslim,” one of which is visiting the sick. According to another version: “The rights of one Muslim over another are…” Al-Bukhaari said: Chapter on the obligation of visiting the sick, and he narrated the words of the Prophet (peace and blessings of Allaah be upon him): “Feed the hungry, visit the sick and free the captives.” End quote.
This hadeeth indicates that it is obligatory, and may be understood as meaning that it is a communal obligation, like feeding the hungry and freeing the captives. Al-Nawawi narrated that there is scholarly consensus that it is not waajib (obligatory). Al-Haafiz said in al-Fath (10/117): i.e., it is not obligatory for individuals.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said in al-Sharh al-Mumti’ (5/173):
The correct view is that it is a communal obligation, and the Muslims are obliged to visit their sick. End quote.
The virtue of visiting the sick
There are many ahaadeeth which speak of its virtue, such as the words of the Prophet (peace and blessings of Allaah be upon him): “When the Muslim visits his (sick) Muslim brother, he is harvesting the fruits of Paradise until he returns.” Narrated by Muslim, 2568.
The reward attained by the one who visits the sick is likened to the harvest reaped by one who gathers fruit.
According to al-Tirmidhi (2008), the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Whoever visits a sick person or visits a brother in Islam, a caller cries out to him: ‘May you be happy, may your walking be blessed, and may you occupy a dignified position in Paradise’.” Classed as hasan by al-Albaani in Saheeh al-Tirmidhi.
Imam Ahmad narrated that Jaabir (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Whoever visits a sick person is plunging into mercy until he sits down, and when he sits down he is submerged in it.” Classed as saheeh by al-Albaani in al-Silsilah al-Saheehah, 2504.
Al-Tirmidhi (969) narrated that ‘Ali (may Allaah be pleased with him) said: I heard the Messenger of Allaah (peace and blessings of Allaah be upon him) say: “There is no Muslim who visits a (sick) Muslim early in the morning but seventy thousand angels send blessings upon him until evening comes, and if he visits him in the evening, seventy thousand angels send blessings upon him until morning comes, and he will have a garden in Paradise.” Classed as saheeh by al-Albaani in Saheeh al-Tirmidhi.
Visiting the sick does not involve only those whom you know, rather it is prescribed for those whom you know and those whom you do not know. This was stated by al-Nawawi in Sharh Muslim.
Definition of the sick person whom it is obligatory to visit
It is the sick person whose sickness is preventing him from seeing people. If he is sick but he is still going out and seeing people, then it is not obligatory to visit him.
Al-Sharh al-Mumti’, 5/171