question #3 Sahih Muslim 731a, Book 6, Hadith 134 : What does the practice of reciting the Qur’an in a sitting position during night prayer signify in terms of physical ability and devotion?

I did not see the Messenger of Allah (ﷺ) reciting (the Qur’an) in the night prayer in a sitting position, till he grew old and then he recited (it) in a sitting position, but when thirty or forty verses were left out of the Surah, he would then stand up, recite them and then bowed.