Musannaf Ibn Abi Shayba 13:2482

Abu Bakr narrated to us, he said: Abu Khalid al-Ahmar narrated to us, from Yahya ibn Sa'id, he said: I asked Sa'id ibn al-Musayyib about an orphan of mine who has land. He said: If you are leasing it out, then lease it out for gold or silver.