[Machine] I have never seen the Messenger of Allah, ﷺ , deliver a sermon on Friday while sitting down. Whoever told you that they saw him delivering a sermon while sitting down has lied. Samaak said that Jabir ibn Samurah said, "The prayer of the Messenger of Allah, ﷺ , and his sermon were intentional." And Jabir ibn Samurah also said, "The Messenger of Allah, ﷺ , used to deliver the sermon while standing, then he would sit, and then he would stand again and deliver the sermon."
مَا رَأَيْتُ رَسُولَ اللهِ ﷺ يَخْطُبُ يَوْمَ الْجُمُعَةِ قَطُّ إِلَّا وَهُوَ قَائِمٌ فَمَنْ حَدَّثَكَ أَنَّهُ رَآهُ يَخْطُبُ وَهُوَ قَاعِدٌ فَقَدْ كَذَبَ قَالَ وَقَالَ سِمَاكٌ قَالَ جَابِرُ بْنُ سَمُرَةَ كَانَتْ صَلَاةُ رَسُولِ اللهِ ﷺ وَخُطْبَتُهُ قَصْدًا وقَالَ جَابِرُ بْنُ سَمُرَةَ كَانَ رَسُولُ اللهِ ﷺ يَخْطُبُ قَائِمًا ثُمَّ يَجْلِسُ ثُمَّ يَقُومُ فَيَخْطُبُ