A.T. Robertson Commentary Acts 21:27

"And when the seven days were almost completed, the Jews from Asia, when they saw him in the temple, stirred up all the multitude and laid hands on him," — Acts 21:27 (ASV)

The seven days (α επτα ημερα). For which Paul had taken the vow, though there may be an allusion to the pentecostal week for which Paul had desired to be present (20:16). There is no necessary connexion with the vow in 18:15. In 24:17 Paul makes a general reference to his purpose in coming to Jerusalem to bring alms and offerings (προσφορας, sacrifices). Paul spent seven days in Troas (20:6), Tyre (21:4), and had planned for seven here if not more. It was on the last of the seven days when Paul was completing his offerings about the vows on all five that the incident occurred that was to make him a prisoner for five years.

When they saw him in the temple (θεασαμενο αυτον εν τω ιερω). First aorist middle participle of θεαομα (from θεα, a view, cf. theatre) to behold. In the very act of honouring the temple these Jews from Asia raise a hue and cry that he is dishonouring it. Paul was not known by face now to many of the Jerusalem Jews, though once the leader of the persecution after the death of Stephen and the outstanding young Jew of the day. But the Jews in Ephesus knew him only too well, some of whom are here at the pentecostal feast. They had plotted against him in Ephesus to no purpose (Acts 19:23–41; Acts 20:19), but now a new opportunity had come. It is possible that the cry was led by Alexander put forward by the Jews in Ephesus (19:33) who may be the same as Alexander the coppersmith who did Paul so much harm (2 Timothy 4:14). Paul was not in the inner sanctuary (ο ναος), but only in the outer courts (το ιερον).

Stirred up all the multitude (συνεχεον παντα τον οχλον). Imperfect (kept on) active of συνχεω or συνχυνω (-υννω), to pour together, to confuse as in Ac 2:6; 9:22; 19:31,32; 21:31 and here to stir up by the same sort of confusion created by Demetrius in Ephesus where the same word is used twice (19:31,32). The Jews from Ephesus had learned it from Demetrius the silversmith.

Laid hands on him (επεβαλαν επ' αυτον τας χειρας). Second aorist (ingressive, with endings of the first aorist, -αν) active indicative of επιβαλλω, old verb to lay upon, to attack (note repetition of επ). They attacked and seized Paul before the charge was made.