Musannaf Ibn Abi Shayba 3:3199

Affan narrated to us, he said: Abd al-Wahid narrated to us, he said: Yunus narrated to us: Al-Hasan used to throw pebbles at the poor on Friday while the Imam was delivering the sermon, saying to them: "Sit down." He said: And Ikrimah did not consider [the obligation of] Friday [prayer] to be upon them.