Musannaf Ibn Abi Shayba 34:140

Muhammad ibn al-Hasan narrated to us, Yazid ibn Ibrahim narrated to us, from Layth, from Mujahid, regarding His saying: "The Lote Tree of the Utmost Boundary" (Sidrat al-Muntaha). He said: "It is the first day of the Hereafter and the last day of the world, and it is where [everything] ends."