´It was narrated that Aishah said:` "The Messenger of Allah (ﷺ) used to recite sitting, and when he wanted to bow he would stand up for as long as it takes a person to recite forty verses."
Hadith ReferenceSunan an-Nasa'i / The Book of Qiyam Al-Lail (The Night Prayer) and Voluntary Prayers During the Day / Hadith: 1651
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:صحيح مسلم
Hadith Takhrij«صحیح مسلم/المسافرین 16 (731)، سنن ابن ماجہ/الإقامة 140 (1226)، (تحفة الأشراف: 17950)، مسند احمد 6/217 (صحیح)»