Umm Abdillah mentioned:
I benefited from my father Imam Muqbil:
“The one who sits on a chair isn’t obligated to pray Tahiyatul Masjid because the prophet صلى الله عليه و سلم used to separate between the two sermons of Jumuah with a sitting”
Umm Abdillah mentioned the point of reference for using this as evidence is that the prophet صلى الله عليه و سلم would not come out to the Masjid on the day of Jumuah except at the time of the Khutbah. He would ascend the Minbar and wouldn’t pray Tahiyatul Masjid and if he finished the first sermon, he would sit on the Minbar.
As reported by Bukhari (928) from Ibn Umar Radiallahu Anhumaa
“The prophet صلى الله عليه و سلم used to give two sermons and sit between them”
Majid Jawed Al-Afghanee