From Sahih Bukhari (Hadith 404):
Narrated `Abdullah:"Once the Prophet (ﷺ) offered five rak`at in Zuhr prayer. He was asked, "Is there an increase in the prayer?" The Prophet (ﷺ) said, "And what is it?" They said, "You have prayed five rak`at.' So he bent his legs and performed two prostrations (of Sahu)
Reference: Bukhari 404