Acts 21:23

Therefore do just what we tell you. We have four men who have taken a vow;

Acts 18:18

Paul stayed for a while longer, and then told the brothers and sisters goodbye and sailed for Syria; and he was accompanied by Priscilla and Aquila. At Cenchrea [the southeastern port of Corinth] he had his hair cut, because he was keeping a [Nazirite] vow [of abstention].

Numbers 6:2-7

“Say to the sons of Israel, ‘When a man or a woman makes a special vow, the vow of a Nazirite, that is, one separated and dedicated to 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
Paul stayed for a while longer, and then told the brothers and sisters goodbye and sailed for Syria; and he was accompanied by Priscilla and Aquila. At Cenchrea [the southeastern port of Corinth] he had his hair cut, because he was keeping a [Nazirite] vow [of abstention].
Numbers 6:2
“Say to the sons of Israel, ‘When a man or a woman makes a special vow, the vow of a Nazirite, that is, one separated and dedicated to the Lord,