It is narrated from Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Written on the gate of Paradise is: Muhammad (peace and blessings be upon him) is the Messenger of Allah; Ali (may Allah be pleased with him) is the brother of the Messenger of Allah (peace and blessings be upon him), two thousand years before the heavens and the earth were created."
Imam al-Tabarani (may Allah have mercy on him) said: "No one narrated this hadith from Mis'ar except Ash'ath, the cousin of al-Hasan bin Salih, and no one narrated it from Ash'ath except Yahya bin Salim, and Zakariyya bin Yahya al-Kisa'i is alone in narrating it."
Hadith Referenceالمعجم الأوسط / باب الميم / 5498
Hadith Gradingمحدثین:إسناده ضعيف لضعف أشعث ابن عم الحسن بن صالح
Hadith Takhrij«قال الهيثمي: فيه أشعث ابن عم الحسن بن صالح وهو ضعيف ولم أعرفه «مجمع الزوائد ومنبع الفوائد، ج 9، ص 111»»