Hadith 3:38
Al-Bukhari related on the authority of Abu Hurairah, “Whoever accompanies the funeral of a Muslim, seeking the reward only from Allah, the Almighty, and he stays with it until he offers the funeral prayer and the burial is completed, will return back with two Qirat, each Qirat is equal to the mount of Uhud.”
وَلِلْبُخَارِيِّ: { مَنْ تَبِعَ جَنَازَةَ مُسْلِمٍ إِيمَانًا وَاحْتِسَابًا, وَكَانَ مَعَهُ حَتَّى يُصَلَّى عَلَيْهَا وَيُفْرَغَ مِنْ دَفْنِهَا فَإِنَّهُ يَرْجِعُ بِقِيرَاطَيْنِ, كُلُّ قِيرَاطٍ مِثْلُ أُحُدٍ }
Original Reference: Bulugh al-Maram 569