Alqama prayed five rakahs. It was said to him about it, and he asked, "Did I do that?"I gestured with my head, "Yes."He said, "And you too, one-eyed one?"I replied, "Yes."So he performed two prostrations, then narrated to us from Abdullah, from the Prophet ﷺ, that he once prayed five rakahs. The people whispered to one another, then asked him, "Has the prayer been increased?"He said, "No."They informed him of what had happened, so he folded his leg and performed two prostrations, then said, "I am only a human being. I forget just as you forget."
أخبرنا محمد بن رافع قال حدثني يحيى بن آدم قال حدثنا مفضل بن مهلهل عن الحسن بن عبيد الله
صلى علقمة خمسا فقيل له فقال ما فعلت قلت برأسي بلى قال وأنت يا أعور فقلت نعم فسجد سجدتين ثم حدثنا عن عبد الله عن النبي ﷺ أنه صلى خمسا فوشوش القوم بعضهم إلى بعض فقالوا له أزيد في الصلاة قال لا فأخبروه فثنى رجله فسجد سجدتين ثم قال إنما أنا بشر أنسى كما تنسون
[sahih] Reported by Muslim, Masajid, chapter on inattentiveness in prayer and the sujud for it, no. 92/572, from the hadith of Hasan bin Ubaydullah, through the same chain, and it is also in al-Kubra, no. 1179.