And Paul [after this] tarried [there] yet a good while, and then took his leave of the brethren, and sailed thence into Syria, and with him Priscilla and Aquila; having shorn [his] head in Cenchrea: for he had a vow.
Note 1 at Ac 18:18: Cenchrea was one of the two seaports of the city of Corinth (see note 1 at Ac 18:1). It was the eastern port located on the Aegean Sea, about five miles from the city. Paul embarked for Syria (see note 1 at Ac 15:23) from this port. There was a church located in Cenchrea that Paul mentioned years later in his letter to the Romans, in association with Phebe (Ro 16:1).
Note 2 at Ac 18:18: It is not clear what this vow was or even who took it. Some people have argued that it was Aquila who took the vow instead of Paul. If people who had made a Nazarite vow became defiled, they had to shave their heads and start over (Nu 6:1-21), but it isn't certain this is the vow that is referred to.