Then Paul took the men - Took them to himself; united with them in observing the ceremonies connected with their vow. To transactions like this he refers in 1 Corinthians 9:20; “And unto the Jews I became as a Jew, that I might gain the Jews; to them that are under the Law, as under the Law, that I might gain them that are under the Law.” Thus, it has always been found necessary, in propagating the gospel among the pagan, not to offend them needlessly, but to conform to their innocent customs in regard to dress, language, modes of traveling, sitting, eating, etc. Paul did nothing more than this. He violated none of the dictates of honesty and truth.
Purifying himself with them - Observing the ceremonies connected with the rite of purification. See the notes on Acts 21:24. This means evidently that he entered on the ceremonies of the separation according to the law of the Nazarite.
To signify - Greek: signifying or making known. That is, he announced to the priests in the temple his purpose of observing this vow with the four men, according to the law respecting the Nazarite. It was proper that such an announcement should be made beforehand, in order that the priests might know that all the ceremonies required had been observed.
The accomplishment ... - The fulfilling, the completion. That is, he announced to them his purpose to observe all the days and all the rites of purification required in the Law, in order that an offering might be properly made. It does not mean that the days had been accomplished, but that it was his intention to observe them, so that it would be proper to offer the usual sacrifice. Paul had not, indeed, engaged with them in the beginning of their vow of separation, but he might come in with hearty intention to share with them. It cannot be objected that he meant to impose on the priests, and to make them believe that he had observed the whole vow with them, for it appears from their own writings (Bereshith Rabba, 90, and Koheleth Rabba, 7) that in those instances where the Nazarites had not sufficient property to enable them to meet the whole expense of the offerings, other persons, who possessed more, might become sharers of it, and thus be made parties to the vow. See Jahn’s Archaeology, §395. This circumstance will vindicate Paul from any intention to take an improper advantage, or to impose on the priests or the Jews. All that he announced was his intention to share with the four men in the offering which they were required to make, and thus to show his approval of the thing, and his accordance with the law which made such a vow proper.
Until that an offering ... - The sacrifices required of all those who had observed this vow. See the notes on Acts 21:24. Compare Numbers 6:13. It is a complete vindication of Paul in this case that he did no more here than he had done in a voluntary manner Acts 18:18, and as appears then in a secret manner, showing that he was still in the practice of observing this rite of the Mosaic institution. Nor can it be proved that Paul ever, in any way, or at any time, spoke against the vow of the Nazarite, or that a vow of a similar kind in spirit would be improper for a Christian in any circumstances.