Acts 21:23

This, then, do, which unto thee, we say: - We have four men who have a vow upon themselves.

Acts 18:18

Paul, however, still further abiding a good many days with the brethren, bidding them adieu, set sail for Syria; and, with him, Priscilla and Aquila; having shorn his head in Cenchreae, for he had a vow.

Numbers 6:2-7

Speak unto the sons of Israel, and thou shalt say unto them, - When any man or woman, would make the special vow of One Separate, by separating himself unto Yahweh,

Treasury of Scripture Knowledge

Summary

Do therefore this that we say to thee: We have four men which have a vow on them;

Bible References

We have

Acts 18:18
Paul, however, still further abiding a good many days with the brethren, bidding them adieu, set sail for Syria; and, with him, Priscilla and Aquila; having shorn his head in Cenchreae, for he had a vow.
Numbers 6:2
Speak unto the sons of Israel, and thou shalt say unto them, - When any man or woman, would make the special vow of One Separate, by separating himself unto Yahweh,