In the book of Acts, we read of two accounts where people had their hair shaved off because they had taken a vow.  The first account is about the apostle Paul.

Act 18:18  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.

The second account is about four unnamed men.  Paul came to Jerusalem and met with the brethren.  The brethren said:

Act 21:23  Therefore do what we tell you: We have four men who have taken a vow.
Act 21:24  Take them and be purified with them, and pay their expenses so that they may shave their heads, …

What were they doing and why?  Probably, they had taken a Nazirite vow.  What was this Nazirite vow?  The Nazarite vow is described in Numbers 6.

Num 6:1  Then the LORD spoke to Moses, saying,
Num 6:2  “Speak to the children of Israel, and say to them: ‘When either a man or woman consecrates an offering to take the vow of a Nazirite, to separate himself to the LORD,

We see here that the purpose of a Nazirite vow was to separate yourself to God.

Num 6:3  he shall separate himself from wine and similar drink; he shall drink neither vinegar made from wine nor vinegar made from similar drink; …

1^st requirement was to avoid alcohol and vinegar.

…neither shall he drink any grape juice, nor eat fresh grapes or raisins.
Num 6:4  All the days of his separation he shall eat nothing that is produced by the grapevine, from seed to skin.

2^nd requirement was to avoid all products of the vine.

Num 6:5  ‘All the days of the vow of his separation no razor shall come upon his head; until the days are fulfilled for which he separated himself to the LORD, he shall be holy. Then he shall let the locks of the hair of his head grow.

3^rd requirement was to not cut your hair.  That meant growing a beard if you were a man.

Num 6:6  All the days that he separates himself to the LORD he shall not go near a dead body.
Num 6:7  He shall not make himself unclean even for his father or his mother, for his brother or his sister, when they die, because his separation to God is on his head.
Num 6:8  All the days of his separation he shall be holy to the LORD.

4^th requirement was to avoid dead bodies.

Numbers 6:9-12 give instruction on what to do if he came in contact with a dead body.  He had to shave his head, make an offering and start all over again.

Numbers 6:13-21 give instruction on what to do at the end of the vow.  He had to present to God: a male lamb as a burnt offering, a ewe lamb as a sin offering, a ram as a peace offering, and grain and drink offerings.  Then he had to shave his head and put his hair on the fire with the peace offering.  After all the offerings he could drink wine again.

While the Bible doesn’t give us the reasons for the four requirements, the important thing is the purpose.  The purpose of a Nazirite vow was to separate yourself to God.

The Nazirite vow was normally just for a set period of time, maybe a few weeks or months.  At the end of the vow, as we read, the vow taker shaved his head and offered sacrifices.

What Paul and the four men were doing shaving their heads?  They were probably at the end of taking a Nazirite vow.  The next question is why. Why would the apostle Paul and some of the other brethren make a Nazirite vow?

Let’s read the context of what lead to the four men shaving their heads.

Act 21:17  And when we had come to Jerusalem, the brethren received us gladly.
Act 21:18  On the following day Paul went in with us to James, and all the elders were present.
Act 21:19  When he had greeted them, he told in detail those things which God had done among the Gentiles through his ministry.

Paul told the brethren in Jerusalem those things which God had done among the Gentiles.

Act 21:20  And when they heard it, they glorified the Lord. And they said to him, “You see, brother, how many myriads of Jews there are who have believed, and they are all zealous for the law;

There were lots of Jewish converts to Christianity.

Act 21:21  but they have been informed about you that you teach all the Jews who are among the Gentiles to forsake Moses, saying that they ought not to circumcise their children nor to walk according to the customs.

Many of the Jews in Jerusalem thought that Paul was against the Jewish customs.  If you remember, not long before this incident Paul and Barnabas had a big argument with certain church teachers who taught “Unless you are circumcised according to the custom of Moses, you cannot be saved”.  You can read about it in Acts 15.  The apostles met at Jerusalem to resolve this issue and they concluded that circumcision is not required.  Nevertheless, you can see how rumours could have spread that Paul was against circumcision.  Paul was neither for circumcision nor against circumcision.  He said circumcision didn’t matter.  However, he was against those who taught that you must be circumcision to be saved.

With this in mind, let’s continue in verse 22.

Act 21:22  What then? The assembly [of brethren] must certainly meet, for they will hear that you have come.
Act 21:23  Therefore do what we tell you: We have four men who have taken a vow.
Act 21:24  Take them and be purified with them, and pay their expenses so that they may shave their heads, and that all may know that those things of which they were informed concerning you are nothing, but that you yourself also walk orderly and keep the law.

These four men took the vow to show to the concerned Jews that they were not against God’s law, but as we read that they walked orderly and kept the law. 

Earlier, Paul had early done a similar thing with Timothy – he had him circumcised, as it says in Acts 16:3, “because of the Jews”.

Act 16:3  Paul wanted to have him [Timothy] go on with him. And he took him and circumcised him because of the Jews who were in that region, for they all knew that his father was Greek.

Paul taught circumcision was not required, but then he had Timothy circumcised.  Why?  Doesn’t that sound hypocritical of Paul?  The vows and the circumcision of Timothy are related.

Why did Paul and the four men take a vow?  Why did Paul have Timothy circumcised?  Not because they had to, but because of the Jews.  They did these things to reassure the Jewish converts to Christianity that they were not teaching against God’s law, but that simply some of the rituals were no longer required. 

Paul and the four men did these things out of love– to avoid causing unnecessary offense.  That’s what Paul taught in 1 Corinthians regarding eating meat sacrificed to idols.  It is not sinful to eat meat sacrificed to idols, but if it causes your brother offense, then don’t do it.

Paul and the four men took a Nazirite vow and Paul had Timothy circumcised, because of the Jews – out of love for them, to avoid causing unnecessary offense.

And that’s the lesson for us.  We should do our utmost to avoid causing offense if possible.  Sometimes causing offense is unavoidable.  But if we can avoid causing offense, we should.

In conclusion, the four men and Paul shaved their heads probably because of the Nazirite vow they had taken.  The Nazirite vow had four requirements:

1^st was to avoid alcohol and vinegar.

2^nd was to avoid all products of the vine.

3^rd was to not cut your hair.

4^th was to avoid dead bodies.

Paul and the four men took such a vow because of the Jewish converts to Christianity.  They wanted to reassure them that they were not teaching against God’s law.  They did these things out of love– to avoid causing unnecessary offense.  And that’s the lesson for us.  If possible, we should avoid causing offense.