Ammar bin Sa'd (may Allah have mercy on him) says: Sayyiduna Uthman bin al-Azraq (may Allah be pleased with him) came in to us in the mosque on Friday while the imam was delivering the sermon, and he held back (from moving forward) and sat (at the back) in the mosque. We said: May Allah have mercy on you; had you come (forward) to us, it would have been easier for you. He said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Whoever steps over the necks of people on Friday after the imam has come out (for the sermon), or separates two (seated) people, is like one dragging his intestines in the Fire."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 8367