Matthew 18:21 - 22
How Much Should I Forgive?
21 Then Peter came to Him and said, “Lord, how often shall my brother sin against me, and I forgive him? Up to seven times?”
22 Jesus said to him, “I do not say to you, up to seven times, but up to seventy times seven.
Peter uses the number seven, in the Bible the number seven is used figuratively for completeness. What Peter is asking is if he should go to the limit in forgiving.
If seven is completeness then Jesus is telling Peter seventy times seven, for the effect of emphasis, that He needs to have no limit in how much he should forgive.