From Sahih Bukhari (Hadith 3876):
Narrated Abu Musa:We received the news of the departure of the Prophet (to Medina) while we were in Yemen. So we went on board a ship but our ship took us away to An-Najashi (the Negus) in Ethiopia. There we met Ja`far bin Abi Talib and stayed with him till we came (to Medina) by the time when the Prophet (ﷺ) had conquered Khaibar. The Prophet (ﷺ) said, "O you people of the ship! You will have (the reward of) two migrations
Reference: Bukhari 3876