Albert Barnes Commentary Acts 10:48

"And he commanded them to be baptized in the name of Jesus Christ. Then prayed they him to tarry certain days." — Acts 10:48 (ASV)

And he commanded them, etc. Why Peter did not himself baptize them is unknown. But it might be, perhaps, because he chose to make use of the ministry of the brothers who were with him, to prevent the possibility of future objection. If they did it themselves, they could not so easily be led by the Jews to find fault with it.

It may be added, also, that it seems not to have been the practice of the apostles themselves to baptize very extensively. This was left to be performed by others. See 1 Corinthians 1:14–17: Christ sent me not to baptize, but to preach the gospel.

certain days "abide some days"