Numbers 21:18 (KJV)

From thence they removed, and pitched on the other side of Arnon, which is in the wilderness that cometh out of the coasts of the Amorites: for Arnon is the border of Moab, between Moab and the Amorites.

Wherefore it is said in the book of the wars of the LORD, What he did in the Red sea, and in the brooks of Arnon,

And at the stream of the brooks that goeth down to the dwelling of Ar, and lieth upon the border of Moab.

And from thence they went to Beer: that is the well whereof the LORD spake unto Moses, Gather the people together, and I will give them water.

Then Israel sang this song, Spring up, O well; sing ye unto it:

And from Mattanah to Nahaliel: and from Nahaliel to Bamoth:

And from Bamoth in the valley, that is in the country of Moab, to the top of Pisgah, which looketh toward Jeshimon.

And Israel sent messengers unto Sihon king of the Amorites, saying,

Let me pass through thy land: we will not turn into the fields, or into the vineyards; we will not drink of the waters of the well: but we will go along by the king's high way, until we be past thy borders.

And Sihon would not suffer Israel to pass through his border: but Sihon gathered all his people together, and went out against Israel into the wilderness: and he came to Jahaz, and fought against Israel.