Acts 21:24
Them take - Take with you. Join yourself with them.
And purify thyself with them - Join them in observing the forms of purification prescribed by the Law of Moses in the observance of the vow of the Nazarite. The purifying here refers to the vows of sanctity which the Nazarites were to observe. They were to abstain from wine and strong drink; they were to eat no grapes, moist or dried; they were to come near no dead body, nor to make themselves "unclean" for their father, mother, brother, or sister, when they died Numbers 6:3-7; and they were to present an offering when the days of the vow were completed, Numbers 6:8.
And be at charges with them - Share with them the expense of the offerings required when the vow is completed. Those offerings were a ram of a year old for a burnt-offering, a sheep of the same age for a sin-offering, a ram for a thank-offering, a basket of unleavened cakes, and a libation of wine. See Numbers 6:13-20.
That they may shave their heads - The shaving of the head, or the cutting off the hair which had been suffered to grow during the continuance of the vow Numbers 6:5, was an observance indicating that the vow had been performed. Paul was requested to join with them in the expense of the offerings, that thus, the whole of the ceremonies having been observed, their heads might be shaved as an indication that every part of the vow had been complied with.
And all may know - By the fact of your observance of one of the rites of the Mosaic religion, all may have evidence that it is not your purpose or practice to speak contemptuously of those rites, or to undervalue the authority of Moses.
Are nothing - Are untrue, or without any foundation.
Walkest orderly - That you live in accordance with the real requirements of the Law of Moses. To walk, in the Scriptures, often denotes "to live, to act, to conduct in a certain manner." All, probably, that they wished Paul to show by this was, that he was not an enemy of Moses. They who gave this counsel were Christians, and they could not wish him to do anything which would imply that he was not a Christian.