Parsha Vayeira - Chapter 22 - Verses 7 - 10
Avraham says he is wearing the cloak of you my son. He has to change his deep-rooted characteristic of chesed and overpower it with Yitzhak's middos of gevurah.
The greatness of a person is to go against their nature. Someone who is so good, chesed is so easy for them. It is not to minimize the great deeds of them, only that shows that a person is using the nature Hashem gave them. The real GDliness of a person is going against what is easy for them. When it seems like this does not make sense, but this is what Hashem wants me to do right now, even if it goes against my nature. Greatness is a person who is transcending their natural abilities to do what Hashem is expecting of him.