Charles Spurgeon Commentary Acts 22:15-16

"For thou shalt be a witness for him unto all men of what thou hast seen and heard. And now why tarriest thou? arise, and be baptized, and wash away thy sins, calling on his name." — Acts 22:15-16 (ASV)

These two things were necessary; first, he was to be baptized on profession of his faith in Jesus, and then, he was to have in his soul a vivid consciousness that his sins were all washed away. This was not baptismal regeneration, for he was already regenerate. It was, however, the obedience to the Lord's command, which brought with it a sweet reassurance of the forgiveness of his sins.