John Calvin Commentary Deuteronomy 19:1

"When Jehovah thy God shall cut off the nations, whose land Jehovah thy God giveth thee, and thou succeedest them, and dwellest in their cities, and in their houses;" — Deuteronomy 19:1 (ASV)

When the Lord thy God hath cut off the nations. Moses repeats the same precepts which we have just been considering: that, regarding murders, the people should distinguish between an unintentional killing and a crime.

With this purpose, he assigns six cities in which those who have proved their innocence before the judges could rest in peace and concealment.

In short, however, he defines who is to be exempt from punishment: namely, one who has killed his neighbor ignorantly, as we have previously seen. This is just, because the will is the sole source and cause of criminality; therefore, where there is no malicious feeling, there is no crime.

But, to prevent those who are actually guilty from escaping under the pretext of an unintentional killing, a mark of distinction is added: that is, that no hatred should have preceded it. An instance of this is given: if two friends go out together into a wood, and, without any quarrel or wrangling, the head of the axe slips from the hand of one of them and strikes the other.

God, therefore, justly commands that the motive for the killing should be investigated and shows how it is to be ascertained: namely, if there had been any previous animosity, or if any contention had arisen.

For it is incredible that anyone would be so wicked as to rush into such an abominable sin without reason. It must be observed, however, that there was no room for this kind of assessment except in a doubtful case. For if anyone were to stab his neighbor with a drawn sword, or hurl a dart into his chest, the inquiry would be unnecessary, because the guilty intention would be abundantly clear.