It is narrated from Hazrat Jabir (may Allah be pleased with him) that I saw the Prophet (peace and blessings be upon him) delivering the sermon while standing, and then after a short while he would sit down and would not speak to anyone, then he would stand up and deliver the second sermon. Therefore, if anyone among you says that he saw the Prophet (peace and blessings be upon him) delivering the sermon while sitting, he is speaking falsely. By Allah, I have performed more than two thousand prayers with him.
Hadith Referenceمسند احمد / أول مسند البصريين / 20842
Hadith Gradingحکم دارالسلام:صحيح لغيره، م: 862، وهذا إسناد صحيح