This is a parable (an earthly representation of a Heavenly concept) not an actual event.
Jesus told us many times that we cannot expect God to forgive us our sins unless we also forgive others for the wrongs they do to us.
All scripture is quoted from the King James version.
Matthew 6:12 And forgive us our debts, as we forgive our debtors.
Matthew 6:14 For if ye forgive men their trespasses, your heavenly Father will also forgive you:
Matthew 6:15 But if ye forgive not men their trespasses, neither will your Father forgive your trespasses.
Mark 11:25 And when ye stand praying, forgive, if ye have ought against any: that your Father also which is in heaven may forgive you your trespasses.
Mark 11:26 But if ye do not forgive, neither will your Father which is in heaven forgive your trespasses.
Luke 11:4 And forgive us our sins; for we also forgive every one that is indebted to us. And lead us not into temptation; but deliver us from evil.
It must be important for it to be in 3 of the 4 Gospels. Even beyond that Jesus also said:
Luke 6:38 Give, and it shall be given unto you; good measure, pressed down, and shaken together, and running over, shall men give into your bosom. For with the same measure that ye mete withal it shall be measured to you again.
This tells me that we should not expect God to treat us better than we treat each other.
Luke 6:36 and 37
Be ye therefore merciful, as your Father also is merciful. Judge not, and ye shall not be judged: condemn not, and ye shall not be condemned: forgive, and ye shall be forgiven:
As a Christian (which means 'little Christ) We should strive to be as much like him as possible. Yet the good thing about it is as often as we mess up if we are truly sorry and ask for forgiveness he will give it.
Luke 17:4 And if he trespass against thee seven times in a day, and seven times in a day turn again to thee, saying, I repent; thou shalt forgive him.
Notice I said truly sorry, that does not mean you can intentionally sin and just ask for forgiveness.. That doesn't work!