Albert Barnes on Acts 22:16

And now, why tarriest thou? Why dost thou delay, or wait any longer? These words are not recorded by Luke in Acts 9, where he has given an account of the conversion of Paul; but there is nothing here contradictory to his statement.

And wash away thy sins. Receive baptism, as an act expressive of the washing away of sins. It cannot be intended that the external rite of baptism was sufficient to make the soul pure, but that it was an ordinance divinely appointed as expressive of the washing away of sins, or of purifying the heart. Comp. Heb 10:22. Sinners are represented in the Scriptures as defiled or polluted by sin. To wash away the sins denotes the purifying of the soul from this polluted influence, 1Cor 6:11, Rev 1:5, 7:14, Isa 1:16, Ps 51:2,7.

Calling on the name of the Lord. For pardon and sanctification. Rom 10:13, "Whosoever shall call upon the name of the Lord shall be saved." It was proper that this calling on the name of the Lord should be connected with the ordinance of baptism. That ordinance was expressive of a purifying which the Lord only could produce. It is proper that the rite of baptism should be attended with extraordinary prayer; and that he who is to be baptized should make it the occasion of peculiar and very solemn religious exercises. The external rite will avail nothing without the pardoning mercy of God.

(*) "tarriest" "delayest" (e) "wash away" Heb 10:22, 1Pet 3:21 (f) "calling" Rom 10:13, 1Cor 1:2