Thauban, the freed slave of the Messenger of Allah (ﷺ) reported Allah's Messenger (ﷺ) as saying:He who offered prayer for the dead, for him is the reward of one qirat, and he who attended its burial, he would have two qirats as his reward. And qirat is equivalent to Uhud.
وَحَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا يَحْيَى، - يَعْنِي ابْنَ سَعِيدٍ - حَدَّثَنَا شُعْبَةُ، حَدَّثَنِي قَتَادَةُ، عَنْ سَالِمِ بْنِ أَبِي الْجَعْدِ، عَنْ مَعْدَانَ بْنِ أَبِي طَلْحَةَ الْيَعْمَرِيِّ، عَنْ ثَوْبَانَ، مَوْلَى رَسُولِ اللَّهِ صلى الله عليه وسلم أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " مَنْ صَلَّى عَلَى جَنَازَةٍ فَلَهُ قِيرَاطٌ فَإِنْ شَهِدَ دَفْنَهَا فَلَهُ قِيرَاطَانِ الْقِيرَاطُ مِثْلُ أُحُدٍ " .
Muslim
The Book of Prayer - Funerals • Hadith 74