ליטעראַטור פֿון בית שני אויף שמות 7:20

[259] Thus our investigation has shewn what was meant when the speech which deserves praise was compared to a river. It follows that speech which calls for censure was none other than the river of Egypt—speech, that is, which is ill-trained, ignorant and practically soulless. And therefore it changes into blood (Ex. 7:20), since it cannot provide nourishment, for the speech of indiscipline none can drink. And further it is prolific of frogs, bloodless, soulless creatures, whose cry is a strange harsh noise, painful to the hearers.