Q. Should one who visits the sick wear Shabbos or better clothing, since he is doing a mitzva? (Re- question above)
A. Talmud (Brochos 12b) teaches that on who goes to visit the ill, should cover himself since the presence of the Shechina rest over the head of the patient. (Shulchan Aruch 325: 3).
The Sheloh Hakadosh (2: Peshachim) and Meam Loez (Vayera) write that he should dress and cover himself with honorable clothing, as he would do when attending shul to daven.
As mentioned above, Horav Shlomo Miller’s Shlit’a opinion is that one should wear bigdei kavod when complying with a mitzva.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a