"I saw the Messenger of Allah ﷺ delivering the khutbah on Friday standing, then he sat briefly and did not speak, then he stood up and delivered a second khutbah. So whoever tells you that the Messenger of Allah ﷺ used to deliver the khutbah seated, he has lied." (Using translation from Nasāʾī 1417)
سَمِعْتُ جَابِرَ بْنَ سَمُرَةَ يَقُولُ «رَأَيْتُ النَّبِيَّ ﷺ يَخْطُبُ يَوْمَ الْجُمُعَةِ قَائِمًا ثُمَّ يَقْعُدُ فَلَا يَتَكَلَّمُ ثُمَّ يَقُومُ فَيَخْطُبُ خِطْبَةً أُخْرَى فَمَنْ حَدَّثَكَ أَنَّ رَسُولَ اللهِ ﷺ خَطَبَ قَاعِدًا فَقَدْ كَذَبَ»