I'm trying to remember the location and exact wording of a few verses in the Bible: the disciples were talking?

to Jesus about someone who refused to give them lodging, I think, and one disciple suggested that they should curse this person according to a particular curse mentioned in the Bible, I think. Jesus replied that they didn't understand what they were suggesting. This is not the exact wording but the point was that God is merciful and doesn't enjoy punishing people and would therefore rather not. I hope someone knows what I'm talking about because I would really like to find this text and exactly what it says.