The Prophet ﷺ prayed Dhuhr as five rakahs. It was said, "Has something been added to the prayer?"It was said, "You prayed five." So he performed two prostrations.
حدثنا عمرو بن الهيثم حدثنا شعبة عن الحكم عن إبراهيم عن علقمة
أن النبي ﷺ صلى الظهر خمسا فقيل زيد في الصلاة قيل صليت خمسا فسجد سجدتين
Its isnad is sahih. This is an abridged version, and it appears in al-Muntaqa (1342) with the wording, "It was said, 'Have you added to the prayer?' He said, 'What is that?' They said, 'You prayed five.' So he prostrated twice after finishing, and it was said, the jamaah narrated it."