Charles H. Spurgeon on Psalms 105:30

Their land brought forth frogs in abundance. If fish could not live frogs might, yea, they multiplied both on land and in the water till they swarmed beyond all count. In the chambers of their kings. They penetrated the choicest rooms of the palace, and were found upon the couches of state. The Lord called for them and they marched forth. Obnoxious and even loathsome their multitudes became, but there was no resisting them; they seemed to spring out of the ground, the very land brought them forth. Their universal presence must have inspired horror and disgust which would cause sickness and make life a burden; their swarming even in the king's own chambers was a rebuke to his face, which his pride must have felt. Kings are no more than other men with God, nay less than others when they are first in rebellion; if the frogs had abounded elsewhere, but had been kept out of his select apartments, the monarch would have cared little, for he was a heartless being, but God took care that there should be a special horde of the invaders for the palace; they were more than ordinarily abundant in the chambers of their kings.