Riyad as-Salihin 1174
Ibn Mas'ud (May Allah be pleased with him) reported:
One night I joined the Prophet (ﷺ) in his (optional) Salat. He (ﷺ) prolonged the Qiyam (standing) so much that I made up my mind to commit an act of wrong. He was questioned: "What did you intend to do?" He replied: "I intended to sit down and stop following him (in Salat)." [Al-Bukhari and Muslim] .
وعن ابن مسعود رضي الله عنه، قال‏:‏ صليت مع النبي صلى الله عليه وسلم ، ليلة، فلم يزل قائمًا حتى هممت بأمر سوء‏.‏ قيل‏:‏ ما هممت‏؟‏ قال‏:‏ هممت أن أجلس وأدعه‏.‏ ‏(‏‏(‏متفق عليه‏)‏‏)‏ ‏.‏