The Halachic authorities disagree in identifying the Biblical source for the Mitzva of Bikur Cholim visiting the sick. According to some views, this obligation stems from the command, "Ve'halachta Bi'drachav" (Devarim 28:9), which requires that we follow the Almighty's example. And just as He visits the sick, as in the Book of Bereishit (18:1), when He visited Avraham Avinu after his circumcision, so must we follow this example and visit those who are ill. Others maintain that the source of this obligation is the Mitzva of Hashavat Aveida, which requires returning a lost object to its owner. If the Torah obligates us to return one's material possessions, then we are certainly required to rejuvenate a person's spirits when he experiences pain. Finally, the Rambam held that the obligation to visit the sick stems from the Mitzva of "Ve'ahavta Le'rei'acha Kamocha" ("Love your fellow as yourself" Vayikra 19:18). It should be noted that the Rambam also describes this Mitzva as a law ordained by the Rabbis, which appears to contradict his position that it evolves from the Torah precept of "Ve'ahavta Le'rei'acha Kamocha"; the Rambam's view thus seems somewhat difficult to understand.
According to the second view, that Bikur Cholim has its origins in the law of Hashavat Aveida, the question arises as to whether Torah scholars are included under the obligation to visit the sick. Halacha exempts a Torah scholar from returning a lost article to its owner in situations where this would be beneath his dignity. For example, if a scholar finds a lost chicken, it would be inappropriate for him to carry a chicken with him through the streets looking for its owner, and therefore in such a situation he would be exempt. Perhaps, then, we would exempt a Torah scholar from the Mitzva of visiting a sick patient if this would infringe upon his distinguished stature.
In truth, however, Halacha in fact includes Torah scholars under the Bikur Cholim obligation, even according to the view that this Mitzva stems from the obligation of returning lost objects. The Shita Mekubetzet (a compendium of commentaries to the Talmud from the Rishonim) draws proof to this ruling from the fact that, as mentioned earlier, the Almighty Himself paid a visit to Avraham. If God lowered Himself, so-to-speak, for the purpose of visiting Avraham, then certainly a Torah scholar even of the highest stature must visit a sick patient, even when this might be considered beneath his dignity.
Does the Mitzva of Bikur Cholim apply if the patient is sleeping, or if he is comatose, Heaven forbid?
The Gemara states that a person's very presence by a patient's bedside is beneficial for the patient, regardless of whether or not he speaks, as evidenced by God's visit to Avraham, during which He did not speak to Avraham at all. Therefore, the Rosh (Rabbenu Asher Ben Yechiel, Germany-Spain, 1250-1327) held that one should visit a sick patient even if he is currently sleeping. He advises, however, that the visitor leave the patient a note so that he will know when he wakes that his friend had paid him a visit.
Summary: The obligation of Bikur Cholim, visiting the sick, applies even to distinguished Torah scholars, even if visiting a sick patient might be seen as an infringement upon their honor. Visiting a sick patient is beneficial for him even while he is sleeping or comatose, and thus the Mitzva applies even during these periods; in such a case, the visitor should leave a note informing the patient that he had come to visit.
