It was narrated that Jabir bin Samurah said:

"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."

أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ سِمَاكٍ، عَنْ جَابِرِ بْنِ سَمُرَةَ، قَالَ رَأَيْتُ رَسُولَ اللَّهِ ﷺ يَخْطُبُ قَائِمًا ثُمَّ يَقْعُدُ قَعْدَةً لاَ يَتَكَلَّمُ فِيهَا ثُمَّ قَامَ فَخَطَبَ خُطْبَةً أُخْرَى فَمَنْ خَبَّرَكَ أَنَّ النَّبِيَّ ﷺ خَطَبَ قَاعِدًا فَلاَ تُصَدِّقْهُ .