"Once the Prophet ﷺ offered five rakʿat 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 rakʿat.' So he bent his legs and performed two prostrations (of Sahu).
صَلَّى النَّبِيُّ ﷺ الظُّهْرَ خَمْسًا فَقَالُوا أَزِيدَ فِي الصَّلاَةِ قَالَ وَمَا ذَاكَ قَالُوا صَلَّيْتَ خَمْسًا فَثَنَى رِجْلَيْهِ وَسَجَدَ سَجْدَتَيْنِ