Matt 17:14 ff: A man brings the case of his disturbed son to Jesus, stating he brought the son to Jesus' disciples first, and they couldn't heal him. Jesus responds: “You unbelieving and perverted generation, how long shall I be with you? How long shall I put up with you?"
I can't tell from the text or the context whether Jesus' response is speaking to the disciples, or to the father of the afflicted son. The last part of that interaction, "Bring him here to Me" doesn't really clarify, because it could either be directed to the father or to the unsuccessful disciples.
I'm inclined to think it's the disciples, particularly since He upbraids them for their lack of faith on this topic later, but the Greek word "διεστραμμένη," translated perverse, perverted, corrupt, seems pretty strong language to use on the disciples. However, it also seems pretty strong language to use to a father seeking help for his son.
Other context notes: Jesus has been speaking to his disciples about going to Jerusalem to be betrayed and executed, and He had just been on the mountain talking to Moses and Elijah, accompanied by Peter, James, and John (thus the emphasis on "How long shall I put up with you;" He KNOWS He doesn't have much time on Earth left). He comes off the mountain, approaches the crowd, and the father comes forth. So, possibly, the father has been dealing with the other nine disciples?