Matthew 10:1

And when He had called unto Him His twelve disciples, He gave them power against unclean spirits, to cast them out, and to heal all manner of sickness and all manner of disease.

The first part of Christ's Galilean ministry was over. He had spread the Gospel-message by His personal preaching in all parts of the northern country. But the conditions, as He had just told His disciples, demanded at the same time more general and more intensive work. And so He commissioned His twelve disciples, the twelve that were later distinguished by that name, whose relation to the Lord had been unusually intimate from the first. He had many other disciples or adherents. His Word had not returned void. Most of those that had experienced His healing power had accepted His Gospel and were His true believers. Many of these stayed in their own homes, testifying for the Lord upon occasion. Others, and among them these twelve as the most prominent, accompanied the Lord on all or most of His journeys. The twelve He here called for a special mission. The sum of His charge to them: Power over unclean spirits and power of healing both the severer sicknesses and the infirmities or weaknesses of the people. The authority to heal was especially necessary for the work in Galilee, since the fame of Jesus rested largely upon His miracles, and the populace would naturally demand some proof of their commission, if they claimed to have been sent by Christ.