Second Migration to Abyssinia

In one narration it is stated that Hazrat Uthman (ra) migrated once again to Abyssinia (Ibn Saad, Al-Tabaqat al-Kubra, Vol. 3, Uthman (ra) bin Affan [Beirut, Lebanon: Dar Ihya al-Turath al-Arabi, 1996], p. 31) but in the majority of books of history, there is no mention of Hazrat Uthman (ra) migrating to Abyssinia a second time. As it were, with regard to the background and details of the second migration to Abyssinia that are mentioned in certain books of history and hadith, careful and meticulous historians do not accept them completely as they are because from the historical events, it seems impossible.