“And you shall speak my words to them, whether they will hear, or whether they will forbear, for they are most rebellious.”
The voice of the prophet must continue whether men heard or not. He was given God's words as a sacred trust, and so he must speak. But response was not guaranteed, for he must recognise the rebelliousness of those to whom he went. This continual emphasis was a sign and a warning that soon something very difficult was going to be required of him. God was preparing him for the worst. As we serve God that is the one thing that we can guarantee, that God will prepare us for what is to come.