Sforno on Numbers
ויחרם אתהם ואת עריהם. They vowed at that time to make all this loot holy, property of the Temple Treasury, as we know they did from the beginning of the Book of Judges (Judges 1,17) [possibly the author uses the extraneous word הכנעני in that verse as the reason for linking it to the fulfillment of above vow. Clearly, the Safed mentioned there has nothing to do with the Safed in the north of the Land of Israel we are familiar with. Ed.]
Haamek Davar on Numbers
Yisroel’s voice. They prayed in addition to the vow; prayer that comes from the depths of the heart is called ‘voice’.