"'Umar, may Allah be pleased with him, banished Rabi'ah bin Umaiyah to Khaibar for drinking Khamr, and he went and joined Heraclius and became a Christian. 'Umar, may Allah be pleased with him, said: 'I will never expel any Muslim after this.'" (Using translation from Nasāʾī 5676)  

عُمَرُ «لَا أُغَرِّبُ بَعْدَهُ مُسْلِمًا»