The Prophet ﷺ used to deliver the sermon on Friday, then sit down, then stand up and deliver another sermon. He said, "Just as you do today."
حدثنا حميد بن مسعدة البصري حدثنا خالد بن الحارث حدثنا عبيد الله بن عمر عن نافع
أن النبي ﷺ كان يخطب يوم الجمعة ثم يجلس ثم يقوم فيخطب قال مثل ما تفعلون اليوم
Its authenticity was agreed upon. Bukhari related it in "Friday Prayer," chapter on delivering the sermon while standing, hadith 920, and Muslim, hadith 861, from the hadith of Khalid bin Harith, with the same wording.On this topic, there are also narrations from Ibn Abbas [Ahmad: 1/256], Jabir bin Abdullah [Bukhari, hadith 918], and Jabir bin Samura [Muslim, hadith 862].