Muwatta Malik 266

Yahya related to me from Malik from Abdullah ibn Abi Bakr from his father that Abdullah ibn Qays ibn Makhrama told him that Zayd ibn Khalid al-Juhani said one night that he was going to observe the prayer of the Messenger of Allah, (ﷺ). He said, "I rested my head on his threshold. The Messenger of Allah, (ﷺ), got up and prayed two long, long, long rakas. Then he prayed two rakas which were slightly less long than the two before them. Then he prayed two rakas which were slightly less long than the two before them. Then he prayed two rakas which were slightly less long than the two before them. Then he prayed two rakas which were slightly less long than the two before them. Then he prayed two rakas which were slightly less long than the two before them. Then he prayed an odd raka, making thirteen rakas in all."