It is narrated from Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Do you know who a Muslim is?" The people said: "Allah and His Messenger (peace and blessings be upon him) know best." He (peace and blessings be upon him) said: "One from whose tongue and hand the Muslims are safe." They said: "Then who is a believer?" He (peace and blessings be upon him) said: "One from whom people feel safe regarding their lives and their wealth." They said: "Then who is an emigrant (muhajir)?" He (peace and blessings be upon him) said: "One who abandoned evil and kept away from it."
Only Rawh bin Salah (may Allah have mercy on him) narrated these two hadiths from Musa bin Ulayy (may Allah have mercy on him).
Hadith Referenceالمعجم الأوسط / باب الألف / 232
Hadith Takhrij«أخرجه أحمد فى «مسنده» برقم: 7044، 7138، وعبد بن حميد فى «مسنده» برقم: 336، والطبراني فى «الكبير» برقم: 14610، 14611، والطبراني فى «الأوسط» برقم: 3188»