Re: why !!! give one good reason
Post the hadith here zero1 since I assume you have read it.
No Muslims (let alone a sunni) can curse Ali or ANY sahaba for that matter but on the other hand Shias do curse the very first and finest people that prophet was close to and loved. It is a shame they do not admit it but their books are full of slander against sahaba and their current imams only curse sahaba in their lectures.