Having delivered word of a fair few plagues already, Moshe is told to go see Paroh again, and the reason he is given is quite bizarre:
וַיֹּאמֶר ה אֶל-מֹשֶׁה, בֹּא אֶל-פַּרְעֹה: כִּי-אֲנִי הִכְבַּדְתִּי אֶת-לִבּוֹ -Hashem said to Moshe, “Go see Paroh, because I’ve hardened his heart”. (10:1)
What is the cause and effect in the instruction? Why is the fact Moshe is sent related to Hashem hardening his heart?
The Sfas Emes explains that Paroh’s heart was hardened, meaning his resolve was given the endurance to withstand the plagues. This was the challenge Moshe was sent to address.
The Sfas Emes teaches that every Jew must know that every hurdle and obstacle they will ever face in life is a challenge straight from God. It is precisely because God is testing you that you must rise to the occasion. When a כִּי-אֲנִי הִכְבַּדְתִּי אֶת-לִבּוֹ is placed before us, is precisely when we receive the instruction of בֹּא אֶל-פַּרְעֹה.