And the heart of Pharaoh was hardened
 Instead of being softened, as it seemed to be when under the plague, it became harder and harder when delivered from it: 
 neither would he let the children of Israel go;
 though he had so absolutely promised it, and assured them that he would not keep them, and that they should not stay any longer: 
 as the Lord had spoken by Moses;
 that so his heart would be hardened until the signs and wonders were multiplied upon him, God designed to perform, ( Exodus 4:21 ) ( 7:3 ) .