Hadith 8:2054
Abu Bakr narrated to us, he said: Shareek narrated to us, from Ibrahim ibn Muhajir, from Mujahid, he said: It is not lawful to sell its houses (or real estate).
حدثنا أبو بكر قال حدثنا شريك عن إبراهيم بن مهاجر عن مجاهد قال لا يحل بيع رباعها