The Messenger of Allah ﷺ said, "Whoever prays over a funeral receives one qirat of reward, and whoever attends its burial receives two qirats. Each qirat is like the size of Mount Uhud."
أن رسول الله ﷺ قال: من صلى على جنازة فله قيراط، فإن شهد دفنها فله قيراطان، والقيراط مثل أحد.
Muslim narrated it in the Funerals chapter (946), through several routes from Qatada, from Salim bin Abu Jaad, from Madan bin Abu Talha Yamuri, from Thawban, and he mentioned it.In another version he recorded, the Prophet ﷺ was asked about the qirat, and he said, "Like the size of Uhud."