Mark 6:13

It was usual for the Jews to prescribe oil as a proper thing to anoint the sick; but its virtue in the present instance, when used by the apostles, was not natural but supernatural, and was derived from him who sent them; because this unction always produced a certain and constant cure in those who were anointed. This miraculous gift of healing the sick with oil, which Christ conferred on his apostles, was a prelude or gradual preparation to the dignity to which he raised this unction, when he established it a perpetual rite in his holy Church. (Rutter) --- With oil, &c. This anointing the sick, was at least a figure of the sacrament, which Christ was pleased to institute for the spiritual relief of persons in danger of death: and which is fully expressed by St. James, in his Catholic Epistle. Chap vi. The Council of Trent says this sacrament was instituted in St. Mark, and published in the Epistle of St. James. (Council of Trent, session xiv. canon 1.) (Witham)