Acts 21:23

Do therefore this that we say to you: We have four men who have a vow on themselves;

Acts 18:18

And Paul after this tarried there yet a good while, and then took his leave of the brethren, and sailed from there into Syria, and with him Priscilla and Aquila; having shaved his head in Cenchrea: for he had a vow.

Numbers 6:2-7

Speak unto the children of Israel, and say unto them, When either man or woman shall separate themselves to vow a vow of a Nazarite, to separate themselves unto the LORD:

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
And Paul after this tarried there yet a good while, and then took his leave of the brethren, and sailed from there into Syria, and with him Priscilla and Aquila; having shaved his head in Cenchrea: for he had a vow.
Numbers 6:2
Speak unto the children of Israel, and say unto them, When either man or woman shall separate themselves to vow a vow of a Nazarite, to separate themselves unto the LORD: