Charles Spurgeon Commentary Acts 9:17-18

"And Ananias departed, and entered into the house; and laying his hands on him said, Brother Saul, the Lord, [even] Jesus, who appeared unto thee in the way which thou camest, hath sent me, that thou mayest receive thy sight, and be filled with the Holy Spirit. And straightway there fell from his eyes as it were scales, and he received his sight; and he arose and was baptized;" — Acts 9:17-18 (ASV)

The Lord, even Jesus, that appeared to you in the way as you came, has sent me, that you might receive your sight, and be filled with the Holy Ghost. And immediately there fell from his eyes as it had been scales: and he received sight immediately, and arose, and was baptized.

What else should a believer be, but baptized? It is the very next step he should take after he has found the Saviour.

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.

As he believed in Jesus, it was right that he should confess his faith in the way that Christ appointed.