Paul's Nazarite Vow

Why did Paul take the Nazarite vow?

Paul Nazarite Vow
Acts 21:23-25 Nazarite Vow

Acts 21:26-30 Paul's Nazarite Vow

Acts 21:31-40 Roman Commander
ACTS 21:26  26 Then Paul took the men, and the next day, having been purified with them, entered the temple to announce the expiration of the days of purification, at which time an offering should be made for each one of them.

Was Paul wrong to agree to take the Nazarite vow?
Possibly but not necessarily. Just after his first departure from Corinth, Paul took a Nazarite vow and had his hair cut off at Cenchrea, the eastern port of Corinth, but there is no mention of him making any offering, let alone sin or trespass offering (see Aquila and Priscilla): "So Paul still remained a good while. Then he took leave of the brethren and sailed for Syria, and Priscilla and Aquila were with him. He had his hair cut off at Cenchrea, for he had taken a vow. And he came to Ephesus, and left them there; but he himself entered the synagogue and reasoned with the Jews" (Acts 18:18-19). If the offerings were omitted as implied, Paul may have wanted the consecration part of the Nazarite vow but not the atonement/sin/trespass offering part, which he stripped out. If so, he could have been planning to do the same or praying to the Lord to intervene before the end of the purification period at which time the offerings were supposed to be made.

ACTS 21:27-30  27 Now when the seven days were almost ended, the Jews from Asia, seeing him in the temple, stirred up the whole crowd and laid hands on him, 28 crying out, “Men of Israel, help! This is the man who teaches all men everywhere against the people, the law, and this place; and furthermore he also brought Greeks into the temple and has defiled this holy place.” 29 (For they had previously seen Trophimus the Ephesian with him in the city, whom they supposed that Paul had brought into the temple.) 30 And all the city was disturbed; and the people ran together, seized Paul, and dragged him out of the temple; and immediately the doors were shut.

Did the Lord intervene?
Since the mob "seized Paul, and dragged him out of the temple" (Acts 21:30) just before the seven day purification period ended - "when the seven days were almost ended" (Acts 21:27), Paul and the four men had yet to make the "offering" (Acts 21:26).

Who saw Paul and "stirred up" (Acts 21:27) the crowd?
"Jews from Asia" (Acts 21:27)

Why would they recognize Paul and what would they have against him?
Since they previously had recognized "Trophimus" (Acts 21:29), one of the eight men who had accompanied Paul to Jerusalem, as an "Ephesian" (Acts 21:29), they were probably from Ephesus, where Paul ministered for three years and planted a church that flourished, much to the displeasure of the Ephesian Jews, who would know and welcome an opportunity to accuse Paul.

Why were the "doors ... shut" (Acts 21:30)?
Since the mob was "seeking to kill him" (Acts 21:31), the temple guards probably didn't want Paul's impending death to defile the temple or another gentile allegedly sneaking into the temple.