Shias often quote this narration in order to make takfeer of the Ummayads that cursed Ali.
The narration can be found in Musnad Ahmad 6/323 and other sources, and they go through Abu Ishaaq Al-Sabee’ee, from Abu Abdullah Al-Jadali, from Um Salama.
Al-Albani weakened the narration in Al-Silsila Al-Dha’eefa (2310) and pointed out that Abu Ishaaq Al-Sabee’ee did not claim that he heard from Abu Abdullah. Al-Sabee’ee was a known mudallis, one who would often narrate narrations from people that he did not hear, and thus, the narration is weak.
Furthermore, Abu Abdullah Al-Jadali himself is a problematic narrator, since there is a difference of opinion about him. Ahmad and Yahya strengthened him in Al-Jarh wal Ta’deel by Ibn Abi Hatim, however, Ahmad weakened him in Su’alaat Al-Marruthi (51), while Yahya weakened him in Su’alaat Al-Doori (2428).
Furthermore, Ibn Sa’ad weakened his hadith in his biography in Al-Tabaqat. Ibn Sa’ad also adds, along with others, that he was an extreme Shia and a commander of the army of Al-Mukhtar, who was claimed to be a prophet.
Also, one should remember that Ali did not make takfeer of those that cursed him, which shows that he never applied this hadith in the first place.
In conclusion, the narration is not reliable due to Abu Ishaaq not claiming to have heard it and due to the status of Abu Abdullah Al-Jadali.