Charles Ellicott Commentary Mark 6:13

"And they cast out many demons, and anointed with oil many that were sick, and healed them." — Mark 6:13 (ASV)

Anointed with oil. St. Mark is the only Evangelist who mentions this as the common practice of the disciples, but we learn from James 5:14 that it was afterwards in use, at least, in the churches of Jerusalem and other Jewish communities.

This practice was partly analogous to our Lord’s treatment of the blind and deaf (Mark 7:33; Mark 8:23; John 9:6). That is, it was an outward sign showing the wish to heal and therefore a help to faith. But as the use of oil was more distinctly that of an agent recognised as remedial in the popular therapeutics of the time, it also had the character of uniting (and devout minds have since regarded it in this way) the use of natural outward means of healing with prayer for the divine blessing.

It scarcely needs to be said that this practice had not the slightest affinity with the mediæval so-called sacrament of extreme unction. Although this sacrament may, in theory, still retain a partial secondary connection with the cure of diseases of the body, it is practically never administered until all hope of cure is abandoned. The development of this latter aspect of the usage was obviously a later outgrowth, from a time when the miraculous gift of healing was withdrawn and it became necessary to devise a theory for retaining the practice.