Sahih Bukhari

Narrated Abu Huraira:The Prophet (ﷺ) offered one of the evening prayers (the sub-narrator Muhammad said, ""I think that it was most probably the `Asr prayer"") and he finished it after offering two rak`at only. He then stood near a piece of wood in front of the Mosque and put his hand over it. Abu Bakr and `Umar were amongst those who were present, but they dared not talk to him about that (because of excessive respect for him), and those who were in a hurry went out. They said, ""Has the prayer been reduced?"" A man who was called Dhul-Yadain by the Prophet (ﷺ) said (to the Prophet), ""Has the prayer been reduced or have you forgotten?"" He said, ""Neither have I forgotten, nor has the prayer been reduced."" He said, ""Certainly you have forgotten."" So the Prophet (ﷺ) offered two more rak`at and performed Taslim and then said Takbir and performed a prostration of Sahu like his ordinary prostration or a bit longer and then raised his head and said Takbir and then put his head down and performed a prostration like his ordinary prostration or a bit longer, and then raised his head and said Takbir