Musnad Ahmad

It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: When the day of Friday comes, angels come to every door of the mosque and keep writing the reward of the worshippers according to their order of arrival. Thus, the one who comes first to the Friday prayer receives a reward like that of sacrificing a camel; the one who comes second receives a reward like that of sacrificing a cow; the one who comes third receives a reward like that of sacrificing a ram; then a chicken, then an egg, each according to the reward of giving charity. And when the Imam comes out and sits on the pulpit, the angels fold up their scrolls and sit down to listen to the remembrance.