Deuteronomy 21:4

21:4 and bring the heifer down to a wadi with flowing water, to a valley that is neither plowed nor sown. There at the wadi they are to break the heifer’s neck.

Deuteronomy 23:4

23:4 for they did not meet you with food and water on the way as you came from Egypt, and furthermore, they hired Balaam son of Beor of Pethor in Aram Naharaim to curse you.

tn The combination “a wadi with flowing water” is necessary because a wadi (נַחַל, nakhal) was ordinarily a dry stream or riverbed. For this ritual, however, a perennial stream must be chosen so that there would be fresh, rushing water.

sn The unworked heifer, fresh stream, and uncultivated valley speak of ritual purity – of freedom from human contamination.

tn Heb “hired against you.”