This narrative closely parallels the one in Numbers 21:21-32. In this account Moses emphasized for the people God's faithfulness to them. Note especially verses 25, 29, 30, 31, 33, and 36.
"All the nations under heaven' (v. 25) is an idiomatic hyperbole signifying all the nations in the vicinity; that is, at least from horizon to horizon (under heaven)."37
"The process of Sihon's fall was much the same as that of the fall of . . . the Pharaoh of the Exodus. Each was approached with a request to favor the Israelites (vv. 26-29), which he refused, because the Lord . . . hardened his spirit(v. 30). Each made a hostile advance against Israel (v. 32) and suffered defeat, as the Lord fought for His people (vv. 31, 33ff.)."38
As God had promised His people, "No city was too high"for them (v. 36). Moses gave God all the credit for this victory.
"Apart from the Lord's intention to provide a home and land for God's people, there are two criteria for the destruction of inhabitants of the land: (1) those who oppose God's purpose and promise to Israel--that is, Sihon and Og; and (2) those who seem to pose in a special way the problem of religious contamination and syncretism--that is, the Canaanites and Amorites."39
". . . the divine hardening described here [v. 30] was part of Yahweh's sovereign judgment on a morally corrupt culture."40
