Numbers 21:1

Arad. This was either the name of the king, or of his city, which was situated in the southern parts of Chanaan, and which fell to the share of Hobab, in the tribe of Juda. (Haydock) --- When this king heard, by means of his spies, or was informed that Israel intended to make an irruption into his country like spies, without declaring war, or by the way which their spies had marked out either just before, or in the second year after their exit; or in fine, by the road, which the Septuagint leave untranslated, Athrim, and which means "of the spies," he resolved to be beforehand with them; and, coming suddenly upon them, took some spoils, or, according to the Hebrew, Septuagint, &c., "captives." These, by the ancient laws of war, he might either sell or put to death. Vendere cum possis captivum, ocidere noli. (Horace) (Grotius, Jur. iii. 7.) The Rabbins pretend that this king took fresh courage on account of the death of Aaron, and the consequent disappearance of the cloud, and that he drove the Israelites seven encampments back, as far as Mosera, which they confound with Haseroth.