Sahih Bukhari

Allah's Messenger (ﷺ) said, "(A believer) who accompanies the funeralprocession of a Muslim out of sincere faith and hoping to attainAllah's reward and remains with it till the funeral prayer is offeredand the burial ceremonies are over, he will return with a reward oftwo Qirats. Each Qirat is like the size of the (Mount) Uhud. He whooffers the funeral prayer only and returns before the burial, willreturn with the reward of one Qirat only."