Numbers 20:15
How our fathers went down into Egypt, and we have dwelt in Egypt a long time; and the Egyptians vexed us, and our fathers: How our fathers went down into Egypt, and we have dwelt in Egypt a long time; and the Egyptians vexed us, and our fathers:
The verse recalls how the forefathers went down into Egypt, dwelt there a long time, and were vexed by the Egyptians together with their descendants. It belongs to the message sent to Edom and its king, recounting that past suffering as the background to the request for safe, peaceful passage through Edomite territory.
The appeal came after the long journey in the wilderness, when Israel sought to travel peacefully through the territory of neighboring nations. Edom refused to let Israel pass through, so Israel turned back to travel through the desert again. Afterward Israel asked the Amorite king for permission to cross his country.
The refusal came because Israel had delayed acting on God's word; prompt trust and obedience would have allowed God to lead them through and would have turned Edom's fear into favor. It was unbelief that prevented the intended passage through Edom.