After many decades of slavery to the Egyptian pharaohs, during which time the Israelites were subjected to backbreaking labor and unbearable horrors, G‑d saw the people’s distress and sent Moses to Pharaoh with a message: “Send forth My people, so that they may serve Me.” But despite numerous warnings, Pharaoh refused to heed G‑d’s command. G‑d then sent upon Egypt ten devastating plagues, afflicting them and destroying everything from their livestock to their crops.
The ten plagues were: water turned to blood, frogs, lice, flies, pestilence, boils, hail, locusts, darkness and death of the firstborn. In each of these plagues, we see a stubbornness in Pharaoh which resulted in a hardened heart. Perhaps you have heard Baruch speak about this. G-d did not reach in and harden Pharaoh’s heart. What we see here is a Biblical spiritual truth. If one hears the truth and rejects it, his/her heart will harden against the truth of G-d. We know that when one “sins a little” it is much easier to sin the second time, and the third time, etc.
When we hear the truth of G-d, when we read His Word, we need to heed it immediately and not harden our hearts and resist or reject it. The next time we then hear the truth, we are more inclined to reject it again and then we find ourselves on the slippery slope of our hearts hardening!