Musnad Ahmad 334:25

Yahya ibn Ghaylan narrated to us, he said: Al-Mufaddal—meaning Ibn Fadalah—narrated to us, he said: Yahya ibn Ayyub narrated to me, from Abd al-Rahman ibn Harmalah, from Sa’id ibn Iyas ibn Salamah ibn al-Akwa’, that his father narrated to him, that Salamah arrived in Medina and Buraydah ibn al-Hasib met him and said: "Have you apostatized from your emigration, O Salamah?" He said: "I seek refuge in Allah. I am under permission from the Messenger of Allah, peace and blessings of Allah be upon him. I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'Go out to the desert, O Aslam, and breathe the winds, and dwell in the mountain passes.'" They said: "We fear, O Messenger of Allah, that that will harm our emigration." He said: "You are emigrants wherever you may be."