It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "The one on the right (the angel) is a trustee over the one on the left (the angel). So when the servant does a good deed, he records it tenfold; and when he does a bad deed and the one on the left wants to record it, the one on the right says to him: 'Hold back.' So he holds back. If the servant seeks forgiveness from Allah, it is not recorded; and if he remains silent, it is recorded against him."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7940