Musnad Ahmad 30:702

'Abd al-Razzaq narrated to us, Ma'mar informed us, from Ayyub, from Ibn Sirin, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) prayed Dhuhr or 'Asr, and he performed the taslim after two rak'ahs, then he departed. The hasty people left, and they said: "The prayer has been shortened." Dhu al-Shamalin said: "Has the prayer been shortened, or have you forgotten?" The Prophet (peace and blessings of Allah be upon him) said: "What is Dhu al-Yadayn saying?" They said: "He is telling the truth." So he prayed the two rak'ahs he had left for them, then he prostrated two prostrations while he was sitting, after he had performed the taslim.