1)
What matters did Mordechai write?
1.
Rashi: This Megilah, as it is.
2.
Vilna Gaon: It is like verse 21 says, "to accept on themselves."
3.
Malbim: He saw that Bnei Kerachim did not accept Purim on themselves, for they thought that they were not in danger. He explained the entire matter at length; really they were in danger, for the first letters were not canceled, just miraculously fear of Mordechai was on the Sarim, and they hid the first letters.
