Albert Barnes Commentary Acts 9:24

"but their plot became known to Saul. And they watched the gates also day and night that they might kill him:" — Acts 9:24 (ASV)

But their laying await. Their counsel; their design.

Was known of Saul. It was made known to him. In what way this was communicated we do not know. This design of the Jews against Saul is referred to in 2 Corinthians 11:32–33, where it is said, In Damascus, the governor under Aretas the king kept the Damascenes with a garrison, desirous to apprehend me; and through a window in a basket was I let down by the wall, and escaped their hands.

And they watched the gates. Cities were surrounded by high walls; and of course the gates were presumed to be the only places of escape. As they supposed that Saul, apprised of their designs, would make an attempt to escape, they stationed guards at the gates to intercept him.

In 2 Corinthians 11:32, it is said that the governor kept the city for the purpose of apprehending him. It is possible that the governor might have been a Jew, and one, therefore, who would enter into their views. Or if not a Jew, the Jews who were there might easily represent Saul as an offender, and demand that he be secured; and thus a garrison or guard might be furnished to them for their purpose. See a similar attempt made by the Jews recorded in Matthew 28:14.