Musnad Ahmad 32:361

Muhammad ibn Abi ‘Adi narrated to us, from Humayd, from Anas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "I reached the Lote Tree (Sidrat al-Muntaha), and its fruits were like large water jars, and its leaves were like the ears of elephants. When that which covered it from the command of Allah covered it, it transformed into ruby, or emerald, or something similar to that."