The Sheiltos D’Reb Achai Gaoin (Sheiltah 93) writes: “One who goes to visit one who is sick shouldn’t go alone, rather, he should take another person with”.
The Netziv (Ha’amek Shailah end of s.k. 7) already asks: “That we don’t find this chiddush in any sefer from the Rishonim to the Achronim, and it’s a pela [wondersome].”
In Gilyonei HaShas (Nedorim 39a) R’ Yosef Engel explains: The Sheiltos is not saying that there is an issur to go alone, he is simply saying that the one visiting should make sure that other people also come to visit, as the more people there are the easier it gets for the sick person, as each person that visits helps remove 1/60th of the illness.
However, the Tzofnas Paneach (Vayechi 48:1) on the pasuk: ויקח את שני בניו עמו – “He took his two sons with him”, which is talking about when Yosef HaTzadik went to visit his father Yaakov who was ill, brings the above Sheiltos and writes:מכאן שיש לקיים מצות ביקור חולים בשנים – “From here we see that one should fulfil the mitzvah of visiting the sick with two.” However, this proof can be easily refuted, as the simple reason he took his two sons with, was so that they could receive a berachah from Yaakov before he was niftar, like Rashi explains.
R’ Asher Weiss (Minchas Asher, Vayera, siman 29, ois 6) offers a novel understanding in the Sheiltos. R’ Mordechai Benet in his chiddushim on Maseches Berachos (18a) writes, that if one missed davening with a minyan, however, there is still another person who hasn’t davened, the two of them should daven together, and it is better for two people to daven together, then to daven alone. Although they both miss out on tefillah betzibbur, they still get the advantage of tefillas rabbim [public prayer]. The Gemara in Berachos (7b) says: “How do we know that Hashem doesn’t despise a tefillas rabbim ...” and two people davening together is a tefillas rabbim. Based on this chiddush, R’ Weiss suggests that this is peshat in the Sheiltos. Since one of the main aspects behind the mitzvah of bikur cholim is to daven for the sick person, one should go together with a friend, and then the tefillah will be a tefillas rabbim, and a more powerful tefillah.
