John Gill Commentary Acts 23:32

"But on the morrow they left the horsemen to go with him, and returned to the castle:" — Acts 23:32 (ASV)

On the morrow they left the horsemen to go with him
That is, the two hundred soldiers, and the two hundred spearmen, who were all on foot, left the seventy horsemen to conduct Paul to Caesarea; for being come to Antipatris, all danger from the Jews was over:

and returned to the castle ;
the castle Antonia in Jerusalem, from whence they set out.