Sahih Muslim 13946
In-book no 6669حَدَّثَنَا أَبُو كُرَيْبٍ، حَدَّثَنَا أَبُو مُعَاوِيَةَ، عَنِ الأَعْمَشِ، بِهَذَا الإِسْنَادِ . نَحْوَهُ غَيْرَ أَنَّهُ قَالَ " فَلَهُ عَشْرُ أَمْثَالِهَا أَوْ أَزِيدُ " .
A hadith like this has been transmitted on the authority of A'mash with the same chain of transmitters and he (further) said: There is for him ten like that (the good he performed) or more than that.