Sahih Bukhari Volume 2, Book 13, Hadith Number 6

Narated By Abu Huraira : Allah’s Apostle (p.b.u.h) said, “Any person who takes a bath on Friday like the bath of Janaba and then goes for the prayer (in the first hour i.e. early), it is as if he had sacrificed a camel (in Allah’s cause); and whoever goes in the second hour it is as if he had sacrificed a cow; and whoever goes in the third hour, then it is as if he had sacrificed a horned ram; and if one goes in the fourth hour, then it is as if he had sacrificed a hen; and whoever goes in the fifth hour then it is as if he had offered an egg. When the Imam comes out (i.e. starts delivering the Khutba), the angels present themselves to listen to the Khutba.”