The Messenger of Allah ﷺ used to pray nine rakahs at night, but when he grew older and his body became heavy, he prayed seven.
كان رسول الله ﷺ يصلي من الليل تسعا، فلما أسن وثقل صلى سبعا.
Nasai (1710) narrated it from Ahmad bin Sulayman, who said, Husayn narrated to us, from Zaida, from Sulayman (Amash), from Umara bin Umayr, from Yahya bin Jazzar, from Ayesha, and he related the same account. Imam Ahmad (24042) narrated it from Muhammad bin Fudayl, from Amash, with the same wording. Abu Muawiya contradicted them, as will come in two places, making it Amr bin Mura instead of Umara bin Umayr, and likewise making the hadith part of the musnad of Umm Salama instead of Ayesha.Daraqutni said in Ilal (5/86) that Ibn Fudayl's version is closer to being correct.Its chain is hasan because of Yahya bin Jazzar Urani, whom Abu Zura, Abu Hatim, Nasai, and Ajli confirmed as reliable, and Ibn Hibban mentioned him among the trustworthy narrators, though there was criticism of his creed. Ibn Saad said, "He went to excess in Shiism, but he was reliable," and he has narrated hadiths.