Musnad Ahmad 1016:13

'Abd al-Razzaq and Ibn Bakr narrated to us, they said: Ibn Jurayj informed us, Ibn Shihab also informed me, from Ibn Buhaynah al-Asadi—and Ibn Bakr said: al-Azdi, an ally of Banu 'Abd al-Muttalib—that the Messenger of Allah (ﷺ) stood up during the Dhuhr prayer while he was supposed to be sitting. When he completed his prayer, he prostrated two prostrations while he was sitting before he performed the taslim, saying the takbir for each prostration. And the people prostrated with him in place of what he had forgotten of the sitting.