Abu al-Aswad al-Du'ali (may Allah have mercy on him) said: Sayyiduna Mu'adh (may Allah be pleased with him) was in Yemen, and people came to him about a Jew who had died and left behind a Muslim brother. Mu'adh (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Islam increases and does not decrease." So he made him an heir.
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17474