Musnad Abu Ya'la al-Mawsili 160:21

Sa'id ibn Yahya ibn Sa'id al-Umawi narrated to us, my father narrated to us, Ibn Jurayj narrated to us, he said: Al-Zuhri narrated to me, from Umar ibn Abd al-Aziz, from Ibrahim ibn Abdullah ibn Qariz, from Abu Hurayrah; and from the hadith of Sa'id ibn al-Musayyib, from Abu Hurayrah, he said: I heard the Prophet, may Allah bless him and grant him peace, saying: "If you say to your companion 'be silent' on the day of Friday while the Imam is delivering the sermon, then you have engaged in idle talk."