I can think of numerous sayings of Jesus and Muhammad that contradict each other. I’m sure if you study you’ll find many but here are just two to get us thinking about the differences in what Jesus said and what Muhammad said.
Jesus said that there is no marriage in heaven.
Muhammad said that in jannah all men will be married to virgins.
Both cannot be right. Who’s speaking the truth? And for what reason would the other one lie???
Jesus said that God is our Father and that we can have a relationship with God as His sons.
Muhammad said that God is not a father and we cannot have any relationship with him except as his slaves.
Both cannot be right. Who’s speaking the truth? And for what reason would the other one lie???