Mark 11:25 in the King James Version
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.
Context
24 Therefore I tell you, all things whatever you pray and ask for, believe that you have received them, and you shall have them.
25 Whenever you stand praying, forgive, if you have anything against anyone; so that your Father, who is in heaven, may also forgive you your transgressions.
26 But if you do not forgive, neither will your Father in heaven forgive your transgressions.”