At the darkest hour of Christ's life, His prayers still focused on forgiveness for the lost. When pain and separation from His Father were weighing down upon Him, to the point of death, He never lost sight of His purpose.
“Father, forgive them, for they know not what they do.” The declaration of their need for forgiveness makes it clear that they were guilty, despite their ignorance. Some sins I willingly and rebelliously commit; others I'm entirely unaware of. Regardless of what motivates my sin, I'm still an indebted sinner, hopelessly lost unless I receive forgiveness.
Upon receiving His forgiveness, Christ says I must offer it to those who have wronged me (Matt. 6:14–15). My tendency is to cling to my pain, to hold it up as evidence as to why I should remain unforgiving toward those who have hurt me. But Christ's example on the cross allows me no room to nurse my grudges.
If I don't yield my pain to Him and respond in accordance with His example, the hurts that I hold onto may become a permanent attachment to my heart. Over time, any pain that I won't address will likely give way to anger, which grows into a grudge, which develops into an unforgiving spirit.
When someone intentionally wounds me, I'm offered the beautiful opportunity to share in Christ's sufferings. But the gospel also dictates how I will respond to those sufferings: die to self and offer the same forgiveness I've been shown.