Sunan an-Nasa'i · Book 14 · Hadith 1415
أَخْبَرَنَا عَلِيُّ بْنُ حُجْرٍ، قَالَ حَدَّثَنَا شَرِيكٌ، عَنْ سِمَاكٍ، عَنْ جَابِرِ بْنِ سَمُرَةَ، قَالَ جَالَسْتُ النَّبِيَّ صلى الله عليه وسلم فَمَا رَأَيْتُهُ يَخْطُبُ إِلاَّ قَائِمًا وَيَجْلِسُ ثُمَّ يَقُومُ فَيَخْطُبُ الْخُطْبَةَ الآخِرَةَ .
It was narrated that Jabir bin Samurah said: "I sat with the Prophet (ﷺ) and I did not see him deliver the khutbah except standing, and he sat, then he stood up and delivered the second khutbah."
Sahih