Muslim recorded it (2/166) and Ahmad (6/222).

Nevertheless, this may appear to be challenged by the report of ʿAbd Allah ibn Abī Qays, who said: “I asked ʿĀʾishah: ‘With how many rakʿahs would the Messenger of Allah ﷺ perform witr?’ She replied: ‘With four and three, six and three, eight and three, and ten and three. He never performed witr with more than thirteen rakʿahs, nor with fewer than seven.’”

Ahmad recorded it (6/149) and Abū Dāwūd (1/214); its chain is sound, as al-ʿIrāqī stated in his Takhrīj al-Iḥyāʾ.

The way to harmonise this narration with her earlier reports is to say that in the latter she was describing his ﷺ normal, predominant practice, whereas here she mentions an increase that occurred on certain occasions, or she included the two light rakʿahs with which he would open his night prayer before the usual eleven.

I say: This is supported by the ḥadīth of Zayd ibn Khālid al-Juhanī, who said, “I resolved to watch the prayer of the Messenger of Allah ﷺ tonight, so I lay down at the threshold of his doorway—or of his tent. The Messenger of Allah ﷺ then prayed two light rakʿahs, then two rakʿahs that were very, very, very long. After that he prayed two rakʿahs shorter than the previous pair, then two shorter than those, then two shorter than those, then two shorter than those, and finally he performed witr, making a total of thirteen rakʿahs.”

It was recorded by Muslim and Abū ʿAwānah in their two Ṣaḥīḥs, and by Ibn Naṣr in Qiyām al-Layl, p. 48. The words enclosed in parentheses are absent from Abū ʿAwānah’s version, though the overall wording is his.

I further suggest that the additional pair may sometimes have been the two sunnah rakʿahs offered after ʿIshāʾ, for I know of no explicit ḥadīth that states he ﷺ prayed ʿIshāʾ, then its sunnah, and then witr as eleven rakʿahs—much less thirteen. In fact, I have found something that supports this possibility: Sharḥabīl ibn Saʿd reported that he heard Jābir ibn ʿAbd Allah say, “We returned with the Messenger of Allah ﷺ from al-Hudaybiyah. When we reached as-Suqyā, the Messenger of Allah ﷺ stood up with Jābir at his side, prayed al-ʿatamah (the late-night ʿIshāʾ), and then performed thirteen prostrations.” Ibn Naṣr transmitted it, and its narrators are trustworthy, except that Sharḥabīl ibn Saʿd became confused in his later years. Allah knows best.