'Aishah (May Allah be pleased with her) reported:
The Messenger of Allah ﷺ did not observe more than eleven Rak'ah (of Tahajjud prayers), be in Ramadan or any other month. First of all he would perform four Rak'ah. Ask not about their excellence and their length. He ﷺ would then perform four more Rak'ah; and do not ask about their excellence and their length. Then he would perform three Rak'ah (Witr prayer). ('Aishah (May Allah be pleased with her) added) I submitted: "O Messenger of Allah! Do you sleep before performing the Witr prayer?" He ﷺ said, "O 'Aishah! My eyes sleep but my heart does not sleep."

[Al-Bukhari and Muslim].

وعنها قالت: ما كان رسول الله ﷺ ، يزيد- في رمضان ولا في غيره- على إحدي عشرة ركعة: يصلي أربعًا فلا تسأل عن حسنهن وطولهن! ثم يصلي أربعًا فلا تسأل عن حسنهن وطولهن! ثم يصلي ثلاثًا. فقلت: يا رسول الله أتنام قبل أن توتر!؟ فقال: "يا عائشة إن عيني تنامان ولا ينام قلبي". ((متفق عليه)) .