Psalms 74:15 - Joseph Benson’s Commentary on the Old and New Testaments

Thou didst cleave the fountain and the flood That is, thou didst, by cleaving the rock, make a fountain in it, and a flood or stream to flow from it, for the refreshment of thy people in those dry deserts. Thou driedst up mighty rivers Hebrew, נהרות איתן rivers of strength. The Seventy, however, render it, ποταμους ηθαμ, taking the latter word, eethan, for a proper name. Undoubtedly Jordan is meant: so that “two other remarkable exertions of the divine power, in favour of the Israelites, are here referred to. Water was brought out of the rock to satisfy their thirst in the time of drought; and the river Jordan was dried up to open the passage for them into Canaan.”