Giving The Khutbah While Standing Sunan Abi Dawud 1093
Translation
Jabir b. Samurah said
The Messenger of Allah (ﷺ) used to deliver the khutbah standing, then he would sit, then stand and deliver the khutbah standing. So whoever tells you that he used to deliver the khutbah sitting has lied. By Allah, I prayed with him more than two thousand prayers.