Yahya related to me from Malik from Abdullah ibn Abi Bakr fromhis father that Abdullah ibn Qays ibn Makhrama told him that Zayd ibnKhalid al-Juhani said one night that he was going to observe theprayer of the Messenger of Allah, may Allah bless him and grant himpeace. He said, "I rested my head on his threshold. The Messenger ofAllah, may Allah bless him and grant him peace, got up and prayed twolong, long, long rakas. Then he prayed two rakas which were slightlyless long than the two before them. Then he prayed two rakas whichwere slightly less long than the two before them. Then he prayed tworakas which were slightly less long than the two before them. Then heprayed two rakas which were slightly less long than the two beforethem. Then he prayed two rakas which were slightly less long than thetwo before them. Then he prayed an odd raka, making thirteen rakas inall."
App reference: Book 7, Hadith 12
USC-MSA web (English) reference: Book 7, Hadith 12
Arabic reference: Book 7, Hadith 266