Acts 23:32

On the morrow they left the horsemen - Being now so far from Jerusalem, they considered Paul in a state of safety from the Jews, and that the seventy horse would be a sufficient guard; the four hundred foot, therefore, returned to Jerusalem, and the horse went on to Caesarea with Paul. We need not suppose that all this troop did reach Antipatris on the same night in which they left Jerusalem; therefore, instead of, they brought him by night to Antipatris, we may understand the text thus - Then the soldiers took Paul by night, and brought him to Antipatris. And the thirty-second verse need not to be understood as if the foot reached the castle of Antonia the next day, (though all this was possible), but that, having reached Antipatris, and refreshed themselves, they set out the same day, on their march to Jerusalem; on the morrow they returned, that is, they began their march back again to the castle. See on Acts 24:1 (note).

They left the horsemen - As they were then beyond the danger of the conspirators, the soldiers who had guarded them thus far returned to Jerusalem.