Hadith 31-309

وَبِإِسْنادِهِ قالَ: قالَ النَّبِيُ‏ صَلَّى اللهُ عَلَيْهِ وَآلِهِ: مَن سَبَّ عَلِيّاً، فَقَدْ سَبَّني وَمَن سَبَّني فَقَدْ سَبَّ اللَّه.

According to the same documentation, the Prophet (S) said, “Whoever swears at Ali has indeed sworn at me, and whoever swears at me has indeed cursed God.”