“The Prophet (ﷺ) offered prayer, I think it was the ‘Asr, and in the second Rak’ah he stood up before he sat. Before he said the Salam, he prostrated twice.”
Sunan Ibn Majah Book 5, Hadith 404
← Previous Hadith “(Once) the Prophet (ﷺ) prayed Zuhr with five Rak’ah, and it was said to him: ‘Has something been added to the prayer?’ He said: ‘What is that?’ They told him, and he turned back towards the Qiblah and performed two prostrations.”

Sunan Ibn Majah Book 5, Hadith 403 Next Hadith → It was narrated from ‘Abdur-Rahman Al-A’raj that Ibn Buhainah told him that the Prophet (ﷺ) stood up in the second Rak’ah of Zuhr and forgot to sit. When he had finished his prayer, and before he said the Salam, he performed the two prostrations for forgetfulness (Sahw) and said the Salam.

Sunan Ibn Majah Book 5, Hadith 405