exodus 8:8 Then Pharaoh called for Moses and Aaron, and said, Intreat the LORD, that he may take away the frogs from me, and from my people; and I will let the people go, that they may do sacrifice unto the LORD. - Free Bible Online

      8-15. Pharaoh called, . . . Intreat the Lord, that he may take away the frogs from me--The frog, which was now used as an instrument of affliction, whether from reverence or abhorrence, was an object of national superstition with the Egyptians, the god Ptha being represented with a frog's head. But the vast numbers, together with their stench, made them an intolerable nuisance so that the king was so far humbled as to promise that, if Moses would intercede for their removal, he would consent to the departure of Israel, and in compliance with this appeal, they were withdrawn at the very hour named by the monarch himself. But many, while suffering the consequences of their sins, make promises of amendment and obedience which they afterwards forget; and so Pharaoh, when he saw there was a respite, was again hardened [Ex 8:15].

JFB.