3 For Matthew, in saying, “They parted His garments, casting lots,” wished it to be understood, that in the whole affair of parting the garments, the coat was also included, on which they cast lots; for in course of parting all the garments, of which it also was one, on it alone they cast lots. To the same purpose also are the words of Luke: “Parting His garments, they cast lots;” for in the process of parting they came to the coat whereon the lot was cast, that the entire parting of His garments among them might be completed.
And what difference is there whether it is said, “Parting they cast lots,” according to Luke; or, “They parted, casting the lot,” according to Matthew: unless it be that Luke, in saying “lots,” used the plural for the singular number—a form of speech that is not unusual in the Holy Scriptures, although some copies are found to have “lot,” and not “lots”? Mark, therefore, is the only one who seems to have introduced any kind of difficulty; for in saying, “Casting the lot upon them, what every man should take,” his words seem to imply, as if the lot was cast on all the garments, and not on the coat alone.
But here also brevity is the cause of the obscurity; for the words, “Casting the lot upon them,” are as if it were said, Casting the lot when they were in the process of division; which was also the case. For the partition of all His garments would not have been complete, had it not been declared by lot which of them also should get possession of the coat, so as thereby to bring any contention on the part of the dividers to an end, or rather prevent any such from arising. In saying, therefore, “What every man should take,” so far as that has to do with the lot, we must not take it as referring to all the garments that were divided; for the lot was cast, who should take the coat: whereof having omitted to describe the particular form, and how, in the equal division that was made of the parts, it remained by itself, in order, without being rent, to be awarded by lot, he therefore made use of the expression, “what every man should take,” in other words, who it was that should take it: as if the whole were thus expressed, They parted His garments, casting the lot upon them, who should take the coat, which had remained over in addition to their equal shares of the rest.
Source: Tractates on the Gospel of John (New Advent)