Sayyiduna Zaid bin Khalid Al-Juhani (may Allah be pleased with him) narrates: He thought, tonight I will observe the prayer of the Prophet Muhammad (peace and blessings be upon him). He says: I sat leaning against the door (perhaps these are the words) outside the tent of the Prophet (peace and blessings be upon him). The Prophet (peace and blessings be upon him) stood up and performed two short rak‘ahs, then he performed two rak‘ahs which were long, then he performed two rak‘ahs which were a little shorter than the previous two rak‘ahs, then he performed two rak‘ahs which were a little shorter than the two before them, then he performed two rak‘ahs which were a little shorter than those two rak‘ahs, then he performed Witr, making a total of thirteen rak‘ahs.