Why did Ashura happen?
Why did imam Hussain rise up?
The following image contains a part of Imam Hussain’s will explaining the main cause of Imam Hussain to rise up and going to Iraq:
اني لم اخرج اشرا و لا بطرا و لامفسدا و لاظالما انما خرجت لطلب الاصلاح في امة جدي و اريد ان امر با لمعروف و انهي عن المنكر
“I did not rise up for the cause of wickedness, amusement, corruption or oppression, but I rose up to reform the Muslim community of my grandfather [Prophet Muhammad (PBUH)]. I want to promote virtue and prevent vice.”
Bihar Al-Anvar: Volume 44, Page 329