Numbers 21:23-26

231But Sihon would not permit Israel to pass through his border. So Sihon gathered all his people and went out against Israel in the wilderness, and came to 2Jahaz and fought against Israel.

24Then 3Israel 4struck him with the edge of the sword, and took possession of his land from the Arnon to the Jabbok, as far as the sons of Ammon; for the 5border of the sons of Ammon was 6Jazer.

25Israel took all these cities and 7Israel lived in all the cities of the Amorites, in Heshbon, and in all her 8villages.

26For Heshbon was the city of Sihon, king of the Amorites, who had fought against the former king of Moab and had taken all his land out of his hand, as far as the Arnon.