Which is better, to spend Qiyam Al-Layl praying sitting, with khushoo and overall feeling comfortable, or to pray standing, tolerating pain because you've standing for some hours, with less or slightly less khushoo than sitting?
Narrated by Ayesha(Ra.),“Do not ever stop praying Qiyaam. The Prophet sallallaahu
alayhi wa sallam ( may Allah exalt his mention ) never ceased praying it. When he sallallaahualayhi wa sallam ( may Allah exalt his mention ) was sick or weak, he prayed sitting.” [Al-Bukhari and Muslim]
Pray standing as much you can comfortably and then pray sitting is better if tired and can't focus.