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 ﷺ ، ليلة، فلم يزل قائمًا حتى هممت بأمر سوء. قيل: ما هممت؟ قال: هممت أن أجلس وأدعه. ((متفق عليه)) .