Sahih Muslim
The Book of Prayers (Kitab Al-Salat)
Book Number: 004 / Hadith Number: 2065
Abu Huraira reported Allah's Apostle (may peace be upon him) as saying: He who offered prayer over the dead, but did not follow the bier, for him is the reward of one qirat, and he who followed it, for him is the reward of two qirats. It was asked what the qirats were. He said: The smaller amongst the two is equivalent to Uhud.