Hastings' Dictionary of the Bible (1898)
JAA'ZER, and JA'ZER (Jehovah helps), a city of Gilead, east of the Jordan, which was conquered and assigned to Gad and to the Levites. Num 21:32; Num 32:1; Josh 21:39. In the time of David it was held by Hebronites or Kohathites, 1 Chr 26:31, but in later times it was subject to Moab, and is often denounced in prophecies against that nation. Isa 16:8-9; Jer 48:32. It was situated at the massive ruins called Sar, about 4 hours (15 miles) north-east of Heshbon. Below the hill is a fountain with a stream which flows to the Jordan.
Tristram found ancient terraces, probably vineyards, in illustration of Isa 16:9; Jer 48:32. There are mounds and rows of foundations at the head of the valley. V. the "Sea of Jazer" is referred to, Jer 48:32; but the passage may be rendered: "Thy shoots have overshot the sea, to Jazer have they reached;" the "sea" would then be the Salt or Dead Sea.