Numbers 21:2 - Coke's Commentary on the Holy Bible

I will utterly destroy their cities— I will utterly devote their cities to destruction. They implored the divine aid by a solemn vow, thus obliging themselves to devote all the persons to death, and their goods to sacred uses. See Leviticus 27:28-29 and Joshua 6:17; Joshua 6:27. Instances of this kind of vow are frequently found amongst the heathens; among the rest, a very remarkable example may be met with in Tacitus. Ann. lib. xiii. c. 57. See also the note on ch. Numbers 22:5.