1st and 4th Google results for the search term “forgiveness repentance”:
https://www.biola.edu/blogs/good-book-blog/2017/can-there-be-forgiveness-without-repentance-part-1 by John E. McKinley (Associate Professor of Biblical and Theological Studies, Talbot School of Theology) — June 21, 2017
https://ethosinstitute.sg/repentance-and-forgiveness/ by Dr Roland Chia, Chew Hock Hin Professor of Christian Doctrine at Trinity Theological College — September 2017
“Overlooked in common Christian understanding of forgiveness is the necessary part of repentance by the wrongdoer.” —link #1
“Broadly, the claim that forgiveness requires repentance fits with the biblical idea of salvation that requires personal faith, the voluntary embrace of God’s gift. God’s forgiveness is available to anyone who would appeal to his mercy, and the appeal includes an acknowledgement of one’s crimes. Forgiveness must be desired and accepted if the sinner is to be forgiven by God. Not all people are included in salvation, since not all people are willing to repent of their sins. Since not even God forgives people apart from their repentance, then why should we expect that we could do so?” —link #1
<quote>However, the majority of Christian theologians and spiritual writers maintain that forgiveness should only be extended to offenders who are truly repentant. Based on passages like Ephesians 4:32, where Paul exhorts his readers to forgive ‘one another, as God in Christ forgave you’, they maintain that we should forgive as God forgives (See also Colossians 3:13).
How does God forgive? It is clear in Scripture that God does not forgive the stiff-necked and unrepentant sinner. In fact, the Bible explicitly teaches that only the repentant will receive divine forgiveness and the blessings of salvation (Mark 1:15; Luke 13:3, 5; Acts 3:19).
There are numerous passages in the NT that underscore that forgiveness is premised on repentance. For example, in Luke 17:3 we read these words of Jesus: ‘Pay attention to yourselves! If your brother sins, rebuke him, and if he repents, forgive him’.
</quote> —link #2
P.S. When I wrote my original post on 07 Aug 2017, the above two excellent articles did not appear on Google’s search results. (Where possible, I prefer to refer people to articles written by actual professional bible scholars / theologians.)
Original post written in 2017: https://caveat1ector.wordpress.com/2017/08/07/forgiveness-involves-repentance/
P.P.S. Apparently there is a common misconception that “forgiveness” simply means not resenting the person emotionally. But this is not what it means in the bible (people commonly mistakenly assume that they know what a word in the bible means simply based on how they themselves use the English word).
Real (biblical) forgiveness is like writing off a debt, so that you no longer require the person to pay back what he owes you. Forgiveness is costly. In a world where every unrepentant evil doer is instantly forgiven, heavy costs are incurred: the evil doer freely gets away with misusing tons of borrowed money; everyone loses.
On the other hand, a repentant debtor who is too poor to pay up, should be forgiven because forgiving him means not throwing him in jail for failure to pay up, which then allows him to be a productive member of the community. Everyone (society) wins.
Cf. “Parable of the unforgiving servant” (Matthew 18:21-) https://www.biblegateway.com/passage/?search=mat+18%3A21-&version=CEB;NIV;NET;NRSV;YLT
P.P.P.S. Further reading: