John Calvin on Deuteronomy 20:15-18

15. Thus shalt thou do unto all the cities. An exception is introduced, that the Jews should not apply the common laws of war to the Canaanitish nations, with respect to whose extermination the sentence had passed. Addition in Fr., “et l’execution commise aux enfans d’Israel;” and its execution committed to the children of Israel. For God had not only armed the Jews to carry on war with them, but had appointed them to be the ministers and executioners of His vengeance. We have elsewhere explained that there were just causes why He would have their race and memory radically destroyed; especially since He had borne with them for four hundred years, whilst in their wicked obstinacy they had not ceased to grow worse and worse, from whence their desperate impiety was manifest. What had been said before is here, however, repeated, i e., that since that land was consecrated to God’s service, its inhabitants were to be exterminated, who could do nothing but contaminate it; and therefore this would be profitable for the Israelites, lest by their wiles they should be attracted to false superstitions.

Deuteronomy 23

Deuteronomy 23:15, 16

15. Thou shalt not deliver unto his master the servant which is escaped from his master unto thee:

15. Non trades servum domino suo, qui se ad te eripuerit a domino suo.

16. He shall dwell with thee, even among you, in that place which he shall choose in one of thy gates, where it liketh him best: thou shalt not oppress him.

16. Tecum habitabit in medio tui, in loco quem elegerit in una urbium tuarum prout placuerit, nec vim inferes ei.