Sunan Abu Dawud
1092
Sahih+3

Ibn 'Umar said:The Prophet (ﷺ) used to deliver two sermons. He would sit down when he ascended the pulpit till he (I think he meant the mu'adhdhin) finished. He would then stand up and preach, then sit down and say nothing, then stand up and preach

SahihAl-Albani
SahihMuhammad Muhyi Al-Din Abdul Hamid