Acts 21:24

γνώσονται for γνῶσι with אABCDE. Vulg. ‘scient.’

24. τούτους παραλαβὼν ἁγνίσθητι σὺν αὐτοῖς, them take and purify thyself with them, i.e. make thyself one of their company, and observe all the ordinances which they observe with regard to purification, and avoiding what is unclean.

καὶ δαπάνησον ἐπ' αὐτοῖς, and be at charges for them. Josephus (Ant. xix. 6. 1) tells how Herod Agrippa took upon him the expenses of many Nazirites (ξυρᾶσθαι διέταξε μάλα συχνούς). Cf. also Bell. Jud. II. 15. 1, from which passage it appears that then the whole time of a Nazirite’s vow was thirty days. This latter passage relates to a vow made by Berenice.

ἵνα ξυρήσονται τὴν κεφαλήν, that they may shave their heads. This use of the future indicative after ἵνα is found in several places in N.T. Whether it occurs in classical Greek is very doubtful; though ὅπως is found with this construction.

The shaving of the head took place at the conclusion of the vow, and when the victims were offered, the hair was burnt in the fire which was under the sacrifice of the peace-offering. The charges which had to be borne by St Paul would be the cost of the victims and other things connected with the sacrifice.

καὶ γνώσονται πάντες, and all shall know, i.e. learning from what they actually behold.

κατήχηνται, they have been informed. See above on Acts 21:21 for the force of the word. They had been taught this calumny about St Paul as if it were a lesson to be learnt.

οὐδέν ἐστιν, are nothing, i.e. have no truth in them. Cf. Acts 25:11.

στοιχεῖς καὶ αὐτὸς φυλάσσων τὸν νόμον, thou thyself also walkest orderly keeping the Law. στοιχέω (as its derivation from στοῖχος = a row, would intimate) is always used of going by a rule or example, following a pattern. What the pattern here is is expressed in the participial clause. Of the value which the Jew attached to such following, cf. Sir 21:11, ὁ φυλάσσων νόμον κατακρατεῖ τοῦ ἐννοήματος αὐτοῦ. He may not understand at first, but obedience will lead him to a mastery of all that the Law means.