John Lightfoot on Mark 6:13

[Anointed with oil many that were sick.] "The oil, therefore, was (saith the famous Beza) a symbol of that miraculous power, not a medicament whereby they cured diseases." But the Jews say, and that truly, such an anointing was physical, although it did not always obtain its end. But this anointing of the apostles ever obtained its end: "R. Simeon Ben Eliezer saith, 'R. Meir permitted the mingling of wine and oil, and to anoint the sick on the sabbath. But when he once was sick, and we would do the same to him, he permitted it not.'" This story is recited elsewhere; where for 'R. Simeon Ben Eliezer,' is 'R. Samuel Ben Eliezer.' Perhaps in the manuscript copy it was written with an abbreviation and thence came the ambiguity of the name.

Let it be granted such anointing was medicinal, which cannot possibly be denied; and then there is nothing obscure in the words of James 5:14; "Let the elders of the church be called, and let the sick man be anointed by them, or by others present, that their prayers may be joined with the ordinary means."