Muwatta Imam Malik (Riwayat Yahya)

It is narrated from Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "When any of you goes to visit a sick person, he enters into the mercy of his Lord, and when he sits there, that mercy settles within him." Or he said something similar to this.

It is narrated from Sayyiduna Ibn Atiyyah (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "There is no ‘adwa (contagion, i.e., one’s illness does not automatically transfer to another), nor is there any haam (the owl, which people consider inauspicious, or the soul of the dead in the form of an animal), nor is there any (evil in) the month of Safar (which people consider inauspicious, and do not consider it good to do any work during the thirteen fasts), but a sick camel should not be brought near a healthy camel. However, the one whose camel is healthy has the choice to settle wherever he wishes." The people asked: What is the reason for this, O Messenger of Allah (peace and blessings be upon him)? He replied: "There is aversion to disease, or it causes discomfort."