The Lord said unto Moses. It seems strange that so fearful an apostasy had gone so far without interference on the part of Moses. He may have been absent from the camp on account of the wars with the Amorite kings; or he may have trusted to the chiefs to see that due order and discipline was maintained in the camps.
Take all the heads of the people, i.e; the chiefs, who ought to have prevented, and might have prevented, this monstrous irregularity, but who seem, if we may judge from the case of Zimri, to have countenanced it.
The mere neglect of duty in so gross a case was reason enough for summary execution. Hang them up before the Lord. Either by way of impalement or by way of crucifixion, both of which were familiar modes of punishment.
In this case the guilty persons were probably slain first, and exposed afterwards. The hanging up was not ordered on account of its cruelty, nor merely for the sake of publicity ("against the sun ), but in order to show that the victims were devoted to the wrath of God against sin (cf.
Deuteronomy 21:23; 2 Samuel 21:2-6). The Septuagint has here παραδειγμάτισον αὐτούς. Cf. Hebrews 6:6, where this word is coupled with "crucify." Them is no authority for referring the "them" ( אוֹתָם) to the guilty persons instead of to the heads of the people, as is done by the Targums and by many commentators.