Mishkat al-Masabih · Book 4 · Hadith 1416
وَعَنْ كَعْبِ بْنِ عُجْرَةَ: أَنَّهُ دَخَلَ الْمَسْجِدَ وَعَبْدُ الرَّحْمَنِ بْنُ أُمِّ الْحَكَمِ يَخْطُبُ قَاعِدًا فَقَالَ: انْظُرُوا إِلَى هَذَا الْخَبِيثِ يَخْطُبُ قَاعِدًا وَقد قَالَ الله تَعَالَى: (وَإِذَا رَأَوْا تِجَارَةً أَوْ لَهْوًا انْفَضُّوا إِلَيْهَا وَتَرَكُوك قَائِما) رَوَاهُ مُسلم
Ka'b b. ‘Ujra said he entered the mosque when ‘Abd ar-Rahman b. Umm al-Hakam was sitting while he preached, and said: Look at this scoundrel who is sitting while he preaches, though God most high has said, “But when they…