If you say to your companion 'listen' on Friday while the Imām is delivering the sermon, you have thus engaged in idle talk

The Prophet (may Allah's peace and blessings be upon him) points out that one of the ethics that should be observed by those who attend the Friday sermon is to listen to the preacher to ponder over the delivered lessons and that whoever speaks - albeit the least of words - while the Imām is giving the sermon and tells someone to "keep silent" or to 'listen' has thus missed the merit of the Friday prayer.