John Gill Commentary Matthew 18:22

"Jesus saith unto him, I say not unto thee, Until seven times; but, Until seventy times seven." — Matthew 18:22 (ASV)

Jesus says to him, I say not to you
Which is as if he had said, observe what I am about to say, I do not agree to what you say to fix the number, "until seven times only", but

until seventy times seven ;
a certain number for an uncertain, see (Genesis 4:24) . Christ's meaning is, that a man should be all the days, and every day of his life, forgiving those that sin against him, as often as they repent and acknowledge their fault; and that no time is to be set for the exercise of the grace of forgiveness; but as often as there are objects and occasions, though ever so many and frequent, it should be used; and which he illustrates by the following parable.