Deuteronomy 2:27
Let me pass through thy land: I will go along by the high way, I will neither turn unto the right hand nor to the left. Let me pass through thy land: I will go along by the high way, I will neither turn unto the right hand nor to the left.
Before this request Israel had passed to the south of Edom and then turned northward toward the promised land over a vast elevated plain. They crossed the brook Zered and passed to the east of Moab in obedience to God's command not to distress the Moabites or contend with them in battle. God would not give Israel the land of Moab, having given Ar to the children of Lot. The same direction was given concerning the Ammonites as also descendants of Lot.
The verse records Moses asking Sihon for peaceful passage through Amorite territory along the direct highway without turning aside to either side. Israel would travel through on foot toward the Jordan. The message was a friendly one sent to the Amorite king at his capital for transit on the desired route. That route lay directly through Amorite territory from the Arnon as far north as the Jabbok. The offer included paying for meat and water while passing through.
The request sought only to cross the land on the way to the land God had given Israel. Sihon met the offer with decided refusal while summoning all the hosts of the Amorites to oppose Israel's progress. Poorly prepared Israel then faced well-armed and well-disciplined forces with superior skill in warfare, so that to all human appearance Israel would be speedily destroyed.
After crossing the river Arnon, Israel advanced to battle the Amorites, won the engagement, and soon took possession of the country of the Amorites. The victory was won by the Captain of the Lord's host fighting for His people. He would have given Israel the same victory thirty-eight years before if Israel had trusted Him.