The Messenger of Allah ﷺ used to pray eleven rakahs, and that was his regular prayer. He would prostrate for as long as it would take one of you to recite fifty verses before raising his head.
أن رسول الله ﷺ كان يصلي إحدى عشرة ركعة، كانت تلك صلاته، يسجد السجدة من ذلك قدر ما يقرأ أحدكم خمسين آية قبل أن يرفع رأسه.
Bukhari reported it in tahajjud (1123) from Abu Yaman, who said, Shuayb informed us, from Zuhri, who said, Urwa informed me that Ayesha informed him.Muslim also reported it in the prayer of the traveler (736) through another route from Ibn Shihab with his chain, except that he did not mention her saying, "He would perform the sajdah of that for as long as it takes one of you to recite fifty verses before he raised his head."