When they reached the place called The Skull, there they crucified him and the two criminals, one on his right, the other on his left. Jesus said, Father, forive them; they do not know what they are doing. Then they cast lots to share out his clothing. (Luke 23: 33,34)
The evangelists give almost no details, but we know that crucifixion is horrible. When we see Christians being crucified today by crazed zealots, we understand the need for the word unspeakable. Instead Luke emphasizes the deep prayer of Jesus from the cross.
Up until the end, Jesus continues to teach us. The first words he speaks from the cross are: Father, forgive. Is it possible to forgive much? Yes. A Jewish pianist whose fingers were crushed by Nazi's in the Second World War sought out the soldier who ruined her to forgive him.
The requirement to forgive is the most difficult part of Christianity. Sometimes we think it's to be sexually pure, but that's not it. Forgiving is much more exacting than sexual morality, or fasting, or prayer regimens or Mass obligations.
Forgiveness doesn't mean: Oh don't worry, no problem. Friends forever! Forgiveness means, I wish you well; I wish you everything you need for salvation. That's the opposite of I hope you burn in hell for eternity. And we hear a lot of that, don't we? And when we forgive - then we're free.