Charles Ellicott Commentary Exodus 9:14

"For I will this time send all my plagues upon thy heart, and upon thy servants, and upon thy people; that thou mayest know that there is none like me in all the earth." — Exodus 9:14 (ASV)

I will ... send all my plagues upon thine heart. —The naturally unyielding heart of Pharaoh, which he had further hardened by his own voluntary action (Exodus 8:15; Exodus 8:32), and which God had begun to harden as a penalty (Exodus 9:12), was now to be softened by a repetition of blow after blow, until it would finally succumb, and yield, and humble itself under the mighty hand of God, and consent to the departure of the whole people, with flocks, and herds, and “little ones.”