Silsilat al-Ahadith al-Sahihah

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "(When the Imam is delivering the sermon on the day of Jumu'ah and) you say to those who are talking, 'Be quiet,' then this will be counted as your idle and vain act."