Jabir b. Samura said that the Messenger of Allah ﷺ used to deliver the sermon while standing. He would then sit down and then stand up and address in a standing posture; and whoever informed you that he (the Holy Prophet) delivered the sermon while sitting told a lie. By Allah. I prayed with him more than two thousand times.  

أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يَخْطُبُ قَائِمًا ثُمَّ يَجْلِسُ ثُمَّ يَقُومُ فَيَخْطُبُ قَائِمًا فَمَنْ نَبَّأَكَ أَنَّهُ كَانَ يَخْطُبُ جَالِسًا فَقَدْ كَذَبَ فَقَدْ وَاللَّهِ صَلَّيْتُ مَعَهُ أَكْثَرَ مِنْ أَلْفَىْ صَلاَةٍ  

The Messenger of Allah ﷺ used to deliver the sermon standing, then he would sit down, then stand and preach standing. If anyone tells you he preached sitting, he is lying. I swear by Allah that I offered along with more than two thousand prayers.  

أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يَخْطُبُ قَائِمًا ثُمَّ يَجْلِسُ ثُمَّ يَقُومُ فَيَخْطُبُ قَائِمًا فَمَنْ حَدَّثَكَ أَنَّهُ كَانَ يَخْطُبُ جَالِسًا فَقَدْ كَذَبَ فَقَالَ فَقَدْ وَاللَّهِ صَلَّيْتُ مَعَهُ أَكْثَرَ مِنْ أَلْفَىْ صَلاَةٍ  

The Messenger of Allah ﷺ used to deliver the sermon standing, then he would sit down, then stand and preach standing. If anyone tells you he preached sitting, he is lying. I swear by Allah that I offered along with more than two thousand prayers. (Using translation from Abū Dāʾūd 1093)   

أَنَّهُ رَأَى رَسُولَ اللهِ ﷺ خَطَبَ قَائِمًا عَلَى الْمِنْبَرِ ثُمَّ يَجْلِسُ ثُمَّ يَقُومُ فَيَخْطُبُ قَائِمًا قَالَ فَقَالَ لِي جَابِرٌ فَمَنْ نَبَّأَكَ أَنَّهُ كَانَ يَخْطُبُ قَاعِدًا فَقَدْ كَذَبَ فَقَدْ وَاللهِ صَلَّيْتُ مَعَهُ أَكْثَرَ مِنْ أَلْفَيْ صَلَاةٍ  

Jabir b. Samura said that the Messenger of Allah ﷺ used to deliver the sermon while standing. He would then sit down and then stand up and address in a standing posture; and whoever informed you that he (the Holy Prophet) delivered the sermon while sitting told a lie. By Allah. I prayed with him more than two thousand times. (Using translation from Muslim 862b)  

أَنَّ رَسُولَ اللهِ ﷺ كَانَ يَخْطُبُ عَلَى الْمِنْبَرِ قَائِمًا ثُمَّ يَجْلِسُ ثُمَّ يَقُومُ فَيَخْطُبُ قَائِمًا فَمَنْ نَبَّأَكَ أَنَّهُ كَانَ يَخْطُبُ جَالِسًا فَقَدْ كَذَبَ فَقَدْ وَاللهِ صَلَّيْتُ مَعَهُ أَكْثَرَ مِنْ أَلْفَيْ صَلَاةٍ  

[Machine] "He saw the Prophet ﷺ delivering a sermon standing on the pulpit, then he sat and then stood again to deliver the sermon standing. Jabir asked me, 'Who told you that he used to deliver the sermon while sitting? He is lying. By Allah, I have prayed with him more than two thousand prayers.'"  

أَنَّهُ رَأَى النَّبِيَّ ﷺ يَخْطُبُ قَائِمًا عَلَى الْمِنْبَرِ ثُمَّ يَجْلِسُ ثُمَّ يَقُومُ فَيَخْطُبُ قَائِمًا قَالَ فَقَالَ لِي جَابِرٌ مَنْ نَبَّأَكَ أَنَّهُ كَانَ يَخْطُبُ قَاعِدًا فَقَدْ كَذَبَ فَقَدْ وَاللهِ صَلَّيْتُ مَعَهُ أَكْثَرَ مِنْ أَلْفَيْ صَلَاةٍ  

The Messenger of Allah ﷺ used to deliver the sermon standing, then he would sit down, then stand and preach standing. If anyone tells you he preached sitting, he is lying. I swear by Allah that I offered along with more than two thousand prayers. (Using translation from Abū Dāʾūd 1093)   

أَنَّ رَسُولَ اللهِ ﷺ كَانَ يَخْطُبُ قَائِمًا ثُمَّ يَجْلِسُ ثُمَّ يَقُومُ فَيَخْطُبُ قَائِمًا فَمَنْ نَبَّأَكَ أَنَّهُ كَانَ يَخْطُبُ جَالِسًا فَقَدْ كَذَبَ فَقَدْ وَاللهِ صَلَّيْتُ مَعَهُ أَكْثَرَ مِنْ أَلْفَيْ صَلَاةٍ