Jami` at-Tirmidhi, Book 2, Hadith 245 (In-Book) ⓘ
Abdullah bin Masud narrated: "The Prophet (S) prayed five (Rakah) for Zuhr, so it was said to him: 'Has the prayer been added to, or have you merely forgotten?' So he (S) performed two prostrations after he had said the Salam."
حَدَّثَنَا إِسْحَاقُ بْنُ مَنْصُورٍ، أَخْبَرَنَا عَبْدُ الرَّحْمَنِ بْنُ مَهْدِيٍّ، حَدَّثَنَا شُعْبَةُ، عَنِ الْحَكَمِ، عَنْ إِبْرَاهِيمَ، عَنْ عَلْقَمَةَ، عَنْ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم صَلَّى الظُّهْرَ خَمْسًا فَقِيلَ لَهُ أَزِيدَ فِي الصَّلاَةِ فَسَجَدَ سَجْدَتَيْنِ بَعْدَ مَا سَلَّمَ . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ .
also referenced under: Hadith 392 (Reference) & Volume 1, Book 2, Hadith 392 (DarusSalam)