A.T. Robertson Commentary Acts 12:4

"And when he had taken him, he put him in prison, and delivered him to four quaternions of soldiers to guard him; intending after the Passover to bring him forth to the people." — Acts 12:4 (ASV)

When he had taken him (πιασας). See on 3:7 for same form.

He put him in prison (εθετο εις φυλακην). Second aorist middle indicative of τιθημ, common verb. This is the third imprisonment of Peter (4:3; 5:18).

To four quaternions of soldiers (τεσσαρσιν τετραδιοις στρατιωτων). Four soldiers in each quaternion (τετραδιον from τετρας, four), two on the inside with the prisoner (chained to him) and two on the outside, in shifts of six hours each, sixteen soldiers in all, the usual Roman custom. Probably Agrippa had heard of Peter's previous escape (5:19) and so took no chances for connivance of the jailors.

After the passover (μετα το πασχα). The passover feast of eight days. "The stricter Jews regarded it as a profanation to put a person to death during a religious festival" (Hackett). So Agrippa is more scrupulous than the Sanhedrin was about Jesus.

To bring him forth (αναγαγειν αυτον). Second aorist active infinitive of αναγω, to lead up, old verb, used literally here. Peter was in the inner prison or lower ward and so would be led up to the judgment seat where Herod Agrippa would sit (cf. John 19:13).

To the people (τω λαω). Ethical dative, in the presence of and for the pleasure of the Jewish people.