The Messenger of Allah ﷺ came upon me when I was sitting thus: having my left hand behind my back and leaning on the fleshy part of it, and said: Are you sitting in the manner of those with whom Allah is angry? (Using translation from Abū Dāʾūd 4848)
مَرَّ بِي رَسُولُ اللهِ ﷺ وَأَنَا جَالِسٌ هَكَذَا وَقَدْ وَضَعْتُ يَدِي الْيُسْرَى خَلْفَ ظَهْرِي وَاتَّكَأْتُ عَلَى أَلْيَةِ يَدِي فَقَالَ أَتَقْعُدُ قَعْدَةَ الْمَغْضُوبِ عَلَيْهِمْ