The people spoke against God and against Moses, "Why have you brought us up out of Egypt to die in the wilderness? For there is no food and no water, and we detest this miserable food."
Then the Lord sent poisonous serpents among the people, and they bit the people, so that many Israelites died.
References for Numbers 21:6
The people came to Moses and said, "We have sinned by speaking against the Lord and against you; pray to the Lord to take away the serpents from us." So Moses prayed for the people.
And the Lord said to Moses, "Make a poisonous serpent, and set it on a pole; and everyone who is bitten shall look at it and live."
References for Numbers 21:8
So Moses made a serpent of bronze, and put it upon a pole; and whenever a serpent bit someone, that person would look at the serpent of bronze and live.
The Israelites set out, and camped in Oboth.
They set out from Oboth, and camped at Iye-abarim, in the wilderness bordering Moab toward the sunrise.
From there they set out, and camped in the Wadi Zered.
From there they set out, and camped on the other side of the Arnon, in the wilderness that extends from the boundary of the Amorites; for the Arnon is the boundary of Moab, between Moab and the Amorites.
References for Numbers 21:13
Wherefore it is said in the Book of the Wars of the Lord, "Waheb in Suphah and the wadis. The Arnon
and the slopes of the wadis that extend to the seat of Ar, and lie along the border of Moab."
References for Numbers 21:15