עַל־כֵּן֙ יֵֽאָמַ֔ר בְּסֵ֖פֶר מִלְחֲמֹ֣ת יְהוָ֑ה אֶת־וָהֵ֣ב בְּסוּפָ֔ה וְאֶת־הַנְּחָלִ֖ים אַרְנֽוֹן׃
wherefore it is said in the book of the Wars of the LORD: Vaheb in Suphah, And the valleys of Arnon,
Read kabbalistic (mystical) interpretation of Numbers 21:14: and classical mystical sources.