Ibn Mas'ud (May Allah be pleased with him) said:
One night I joined the Prophet ﷺ in his (optional) Salat. He prolonged the standing so much that I thought of doing something evil. He was asked: "What did you intend to do?" He replied: "To sit down and leave him".

[Al-Bukhari and Muslim].

التاسع: عن ابن مسعود رضي الله عنه قال: صليت مع النبي ﷺ ليلة، فأطال القيام حتى هممت بأمر سوء! قيل: وما هممت به؟ قال: هممت أن أجلس وأدعه. ((متفق عليه)).