2 Peter 1:21:

For the prophecy came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost.

See also:

All About Healing Services
Can I “Turn On” Gifts of the Spirit at Will?
What Are the Differences Between the Gift of Faith, the Gifts of Healings, and the Working of Miracles?
Can I Pray a Certain Prayer to MAKE God Use Me in Certain Spiritual Gifts?