Is the worshipper required to perform bowing and prostrating from a standing position if praying voluntarily while capable?
Chapter on the Times When Prayer is Prohibited
Al-Mughni
Book of Prayer
Primary text
The worshipper is given a choice regarding bowing and prostrating, whether to perform them from a standing position or from a seated position, because the Prophet, peace be upon him, performed both actions. Aisha reported that the Prophet prayed his night prayer mostly standing until he aged, and he would read while seated, but when intending to bow, he would stand to recite about thirty or forty verses, then bow. Another narration confirms he prayed long nights standing and long nights seated, and if he recited standing, he would bow and prostrate standing, and if he recited seated, he would bow and prostrate seated.
Supporting text
Both Hadiths are considered sound, and the practice is established upon both narrations, as affirmed by Ahmad and Ishaq.