When Allah the Almighty commanded the Muslims to migrate, Hazrat Sa‘d bin Abi Waqas (ra) also migrated to Medina and stayed with his brother Utbah bin Abi Waqas, who was an idolater. Utbah had killed someone in Mecca and thus he fled to Medina and settled there.
(Roshan Sitarey az Ghulam Bari Saif Sahib, Vol. 2, pp. 66-67)
Hazrat Sa‘d (ra) was amongst the first people to migrate.
(Umdatul Qari, Vol. 1, p. 305, Dar-ul-Kutub al-Ilmiyyah, Beirut, 2001)