Acts 9:17-18:

And Ananias went his way, and entered into the house; and putting his hands on him said, Brother Saul, the Lord, even Jesus, that appeared unto thee in the way as thou camest, hath sent me, that thou mightest receive thy sight, and be filled with the Holy Ghost.
And immediately there fell from his eyes as it had been scales: and he received sight forthwith, and arose, and was baptized.

Notes on Acts 9:17-18:

Ananias, like Stephen and Philip, was a layperson who did something great for God.  Imagine the privilege, in retrospect, of having been the one to lay hands on the man who became the Apostle Paul so that he would be filled with the Holy Spirit!  Paul was able to be faithful to his vision because Ananias was faithful to his.  Ananias had to believe with no natural proof that (1) Saul was saved (2) The Lord had appeared to Saul on the way to Damascus, and (3) Saul couldn’t see, but would see after he laid hands on him.  Quite the instructions for a layperson!  Of course, he probably knew that if he had missed God in the matter, he would probably have been one of the first Christians rounded up by Saul!

Paul’s blindness was not caused by the devil, but instead from the glory of God.  Even so, he was healed of his blindness when Ananias laid hands on him.  (There are other cases where people’s bodies just can’t handle a case of the manifested presence of God, so they respond in ways such as falling over that might seem like sickness to an observer.)

See also:

Baptism with the Spirit and Being Filled with the Spirit
Why Do People Fall Over in Healing Lines?
Objection: Acts 8 Proves That the Apostles Had Unique Powers