"I saw the Messenger of Allah ﷺ delivering the Khutbah standing up, then he sat down for a while and did not speak, then he stood up and delivered another Khutbah. Whoever tells you that the Prophet ﷺ delivered a Khutbah sitting do not believe him." (Using translation from Nasāʾī 1583)
«رَأَيْتُ رَسُولَ اللهِ ﷺ يَخْطُبُ قَائِمًا ثُمَّ قَعَدَ قَعْدَةً لَا يَتَكَلَّمُ فِيهَا ثُمَّ قَامَ فَخَطَبَ خُطْبَةً أُخْرَى» فَمَنْ خَبَّرَكَ أَنَّ النَّبِيَّ ﷺ خَطَبَ قَاعِدًا فَلَا تُصَدِّقْهُ