Variantly: "And the heart of Pharaoh was reversed": Scripture hereby apprises us that when Israel left Egypt, its kingdom came to an end, as it is written (Ezekiel 32:19) "Whom have you (Egypt) surpassed in beauty? Descend and be laid to rest with the uncircumcised!"
The Heart of Pharaoh Was Reversed
Mekhilta Tractate Vayehi Beshalach 2:16