Tradition

Allah created seventy thousand angels from the light of Ali’s face. All they do is seek forgiveness for him, for his Shias, and for those who love him until the Day of Judgement.
Al-Manaaqib p 31 Maqtal al-Husain v 1 p 39 Ghaayah al-Maraam p 585 Behaar al-Anwaar v 39 p 275
(The fact that angels seek forgiveness for Ameerul Momineen (a.s.) is just like Allah telling His Messenger (s.a.w.a.) in the Qur’an, “So that Allah may forgive your sins and that which is to come” (Surah Fath (48):2). Mofazzal asked Imam Sadiq (a.s.), “What were the sins of the Prophet that Allah forgave?” The Imam (a.s.) replied, “The Messenger of Allah (s.a.w.a.) had no sins but he asked Allah to make him accountable for all of the sins of his Shias, the Shias of Ali, and the Shias of the Imams from his sons until the Day of Judgement. The Prophet (s.a.w.a.) also asked Allah not to expose the sins of the Shias (for which he accepted to be accountable) in front of the other prophets. So Allah revealed this verse to him which means Allah forgave the sins of Shias.” Tafseer al-Qummi v 2 p 314