The story of נחל ארנון mentioned in last week’s Parsha, is not so well known. Its details are found in מסכת ברכות 54.
The Jews were sitting ducks as they crossed the River Arnon. From above, the enemy had made crevices in the mountains to harm עם ישראל. The miracle was that the mountains converged and crushed the enemy.
The people below were unaware of the miracle. There was a leper by the name of והב who had to travel outside of the rest of the camp. He was last in the long line of עם ישראל. It was והב who noticed the blood that flowed in the river from the fallen adversaries.
This prompted the עם to sing שירת הבאר, the song of the well. The Gemara tells us that we should also sing praises to Hashem, if we visit the sights of great miracles. We must never take Hashem’s kindness for granted.