Jeremiah 34:18 - Ellicott's Commentary On The Whole Bible

When they cut the calf in twain... — The passage is interesting, as showing the survival of one of the oldest rites of Patriarchal times. So, when Jehovah made a covenant with Abraham, the victims that had been slain were cut up and arranged opposite each other, and when the “burning lamp” passed between the pieces it was the token that Jehovah had completed the covenant, even as men complete it (Genesis 15:10-17). The implied thought thus symbolised was that the parties to the contract prayed, as in the analogous case of 1 Samuel 11:7, that they might be torn limb from limb like the victims if they broke the covenant, The antiquity and wide extent of the symbolism is shown by its appearing in the ritual of Greece, as in the phrase ὅρκια τέμνον — to ratify (literally, to cut) oaths, in Homer (Iliad, ii. 124, Od. xxiv. 483, and elsewhere), and the Latin fœdus ferire. In Livy (i. 24) we have both the phrase, the act which it implied, and the prayer which accompanied it, that if the Roman people proved unfaithful to their covenant Jupiter would slay them as the priest slew the victim. “Tu illo die, Jupiter, populum Romanum sic ferito, ut ego hunc porcum hic hodie feriam, tantoque magis ferito, quanto magis potes pollesque.” (“Do thou, Jupiter, on that day so smite the Roman people [if they break the covenant] as I this day smite this swine — yea, so much the more smite them as thou art mightier and more prevailing.”)