Albert Barnes Commentary Acts 23:13

"And they were more than forty that made this conspiracy." — Acts 23:13 (ASV)

Which had made this conspiracy. This oath, sunwmosian, this agreement or compact. This large number of desperate men, bound by so solemn an oath, would be likely to be successful; and Paul's life was therefore in peculiar danger. The manner in which they purposed to accomplish their design is stated in Acts 23:15.