Then the LORD said unto Moses, Now shalt thou see what I will do to Pharaoh: for with a strong hand shall he let them go, and with a strong hand shall he drive them out of his land. With a strong hand - יד חזקה yad chazakah, the same verb which we translate to harden; see Clarke on Exodus 4:21 (note). The strong hand here means sovereign power, suddenly and forcibly applied. God purposed to manifest his sovereign power in the sight of Pharaoh and the Egyptians; in consequence of which Pharaoh would manifest his power and authority as sovereign of Egypt, in dismissing and thrusting out the people. See Exodus 12:31-33.
Related Commentaries of Exodus 6:1
Exodus 6:1
1 Then the LORD said unto Moses, Now shalt thou see what I will do to Pharaoh: for with a strong hand shall he let them go, and with a strong hand shall he drive them out of his land.