We are aware of this sermon Of Imam Ali (A.S). Here Imam Ali (A.S) is expressing dislike towards abuse and only instructing to reveal their deeds.

So where did this abuse culture start from, because Imam Ali (A.S) is clearly disliking it

Secondly in Ziarat e Ashura we send La’an (curse) upon banu ummayiya and it is authentic as its narrators are our Masoom Imams (A.S). However does it not contradict with Imam Ali’s (A.S) sermon?

There are two concepts here:

1- “Sabb” which means to use profane or indecent language. Imam Ali (a) advises his companions not to do that, but rather describe the evil actions of Mu’awiya and his people.

2- “La’an” which means cursing, and basically it means to ask Allah to withdraw his mercy. La’na is the opposite of Rahma. Imam Ali (a) is not talking about that. The Qur’an in many verses curses the evil ones, the deviants, and so on. La’an is a Qur’anic principle. M

For further reference, see:

https://youtu.be/6vZBQcJ0Efo