Comentario sobre Exodo 8:26

ויעתר אל ה׳ AND ENTREATED THE LORD (the verb is the Kal) — he concentrated his energies on prayer. So, too, if it had wished to use the term וַיַעְתִּיר (the Hiphil) it could have used it, and that would have signified, “and he increased words in prayer”. But when it uses an expression denoting “and he did something” (the Kal) it signifies “he prayed much (devoutly)”.

ויעתר, in order for G’d to remove the wild beasts at the time which Pharaoh had requested and in the manner he had asked for. We know that this time Pharaoh did not want to have to contend with the stench of the dead animals as he had had to when the crocodiles died on his territory, but that G’d made all these beasts retreat to where they had been before they had invaded the urban areas of Egypt. (compare verse 27)