Is the right to forgiveness forfeited by mere heartfelt intention, or is its forfeiture dependent on declaration and initiative?

The right of a rightful claimant does not lapse except by his explicit declaration of relinquishment. His mere intention does not entail anything. If he explicitly declares the relinquishment of his right, the other party's obligation is absolved, and his right to claim lapses. However, before such a declaration, the rightful claimant does not incur sin if he demands it. Forgiveness is better, closer to piety, and carries a greater reward.