Musnad Ahmad 1304:28

Hashim narrated to us, he said: Abd al-Hamid narrated to us, he said: Shahr narrated to us, he said: Asma bint Yazid narrated to me: That Abu Dharr al-Ghifari used to serve the Prophet, may God bless him and grant him peace. When he finished his service, he would retreat to the mosque, for it was his house, and he would lie down in it. One night, the Messenger of God, may God bless him and grant him peace, entered the mosque and found Abu Dharr sleeping, stretched out in the mosque. The Messenger of God, may God bless him and grant him peace, nudged him with his foot until he sat up straight. The Messenger of God, may God bless him and grant him peace, said to him: "Do I not see you sleeping?" Abu Dharr said: "O Messenger of God, where else should I sleep? Do I have any house other than it?" The Messenger of God, may God bless him and grant him peace, sat beside him and said to him: "How will you be when they drive you out of it?" He said: "Then I will join the Levant (al-Sham), for the Levant is the land of migration, the land of the gathering, and the land of the prophets, and I will be a man among its people." He said to him: "How will you be when they drive you out of the Levant?" He said: "Then I will return to it, and it will be my house and my dwelling." He said: "And how will you be when they drive you out of it a second time?" He said: "Then I will take my sword and fight for myself until I die." He said: The Messenger of God, may God bless him and grant him peace, smiled at him and steadied him with his hand. He said: "Shall I guide you to what is better than that?" He said: "Yes, may my father and mother be sacrificed for you, O Prophet of God." The Messenger of God, may God bless him and grant him peace, said: "Submit to them wherever they lead you, and be driven by them wherever they drive you, until you meet me, while you are upon that."