In Islamic tradition the two Kirāman kātibīn (Arabic: كراماً كاتبين "honourable scribes"), twin angels who are classified as the mu'aqqibat called Raqīb (رَقِيب "Observer" [to record of the deed]) and 'Atīd (عَتِيد "Prepared" [to record of the deed]), believed by Muslims to record a person's actions, thoughts and feelings. Whether a person is sent to jannat (paradise) or Jahannam (hell/purgatory) is not, however, dependent on whether good deeds outweigh bad deeds; but is ultimately up to God's mercy upon a believer. The Quran refers to them in two places, in 50:16-18 and by name as 'Noble Recorders' in 82:10-12.
The work of the Kiraman Katibin is to write down and record every action, thought, or feeling a person has each day. One angel figuratively sits on the right shoulder and records all good deeds, while another sits on the left shoulder and records all bad deeds.
The Book in which the angels are writing is the cumulative record of a given person's deeds. After that person's death, it is said that on the Day of Judgement each person will be confronted with this record, and the two angels will be present to tell God of what the person did.
These angels are not guardian angels, called in Islamic tradition the mu'aqqibat "followers" (Q.13.10-11). According to many Muslims (see below), each human has two guardian angels, in front and behind him, while the two recorders are located right and left.
Muhammad said: “There is no one among you but he has with him a constant companion (qareen) from among the jinn and a constant companion from among the angels.” They said, “You too, O Messenger of Allah?” He said, “Me too, but Allah has helped me against him (the devil-companion) and he has become Muslim.”