Musannaf Ibn Abi Shayba 3:2133

Shababa narrated to us, from Layth, from Yazid, from ‘Imran ibn Abi Anas, from Abu Salamah, from Abu Hurayrah, that the Prophet (peace and blessings of Allah be upon him) prayed one day and performed the taslim after two rak'ahs, then he turned away. Dhu al-Shimalayn caught up with him and said, "O Messenger of Allah, has the prayer been shortened, or have you forgotten?" He said, "The prayer has not been shortened, nor have I forgotten." He said, "Yes, indeed, by the One who sent you with the truth." So the Prophet (peace and blessings of Allah be upon him) said, "Is Dhu al-Yadayn speaking the truth?" They said, "Yes, O Messenger of Allah." So he prayed two rak'ahs for the people.