Albert Barnes Commentary Acts 23:15

"Now therefore do ye with the council signify to the chief captain that he bring him down unto you, as though ye would judge of his case more exactly: and we, before he comes near, are ready to slay him." — Acts 23:15 (ASV)

You, with the council. With the concurrence or request of the Sanhedrin. It was only by such a request that they had any hope that the commander would remove Paul from the castle.

Signify to the chief captain. This means to send him a message or request.

That he bring him down to you. This means that he should bring him from the castle to the usual meeting place of the Sanhedrin. As this was at some distance from the castle, or the Tower of Antonia, where Paul was, they supposed it would be easy to ambush him and take his life.

Tomorrow. This word is absent from the Syriac, Vulgate, and Ethiopic versions. It is, however, probably the correct reading of the text, as it would be necessary to convene the council and make the request of the tribune, which might require an entire day.

As though you would inquire, etc. This request appeared so reasonable that they did not doubt the tribune would grant it to the council. And though it was obviously a false and wicked pretense, these conspirators knew the character of the persons to whom they addressed themselves so well that they did not doubt they would prevail on the council to make the request. Public justice must have deeply fallen, when it was known that such an iniquitous request could be made with the certain prospect of success.

Before he comes near. This means before he comes near to the Sanhedrin. The great council would thus not be suspected of being privy to the deed. Their plan was: "We will ambush him and murder him on the way." They were, in fact, ready to kill (Psalms 21:11). The plan was well laid, and nothing but the intervention of Providence could have prevented its execution.