Jamieson, Fausset and Brown on Exodus 8:25-32

25-32. Pharaoh called for Moses, ... Go ye, sacrifice to your God in the land, &c.--Between impatient anxiety to be freed from this scourge and a reluctance on the part of the Hebrew bondsmen, the king followed the course of expediency; he proposed to let them free to engage in their religious rites within any part of the kingdom. But true to his instructions, Moses would accede to no such arrangement; he stated a most valid reason to show the danger of it, and the king having yielded so far as to allow them a brief holiday across the border, annexed to this concession a request that Moses would entreat with Jehovah for the removal of the plague. He promised to do so, and it was removed the following day. But no sooner was the pressure over than the spirit of Pharaoh, like a bent bow, sprang back to its wonted obduracy, and, regardless of his promise, he refused to let the people depart.