It wasnarrated from Ibn Buhainah:
"The Prophet (ﷺ) offered prayer,Ithink it was the 'Asr, and in the second Rak'ah he stood upbeforehe sat. Before he said the Salam, he prostrated twice." (PT)
English reference (PT): Vol. 1, Book 5, Hadith 1206 (PT)
Arabic reference (PT): Book 5, Hadith 1263 (PT)