Sahih al-Bukhari 1148
صحيح البخاري#1148SahihNarrated `Aisha:I did not see the Prophet (ﷺ) reciting (the Qur'an) in the night prayer while sitting except when he became old; when he used to recite while sitting, and when thirty or forty verses remained from the Sura, he would get up and recite them and then bow
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 19:29