Mankind needs to know the Messenger, and the Message he conveyed. They have to believe in what he said and obey him. The only way to achieve happiness and success in this world and in the hereafter is to follow the Messenger. By following the Messenger, man will become aware of the details of good and evil, and Allah (swt) will be pleased with him. His guidance comprises good deeds, good speech, and good morals. His speech and conduct are the criteria against which all actions are measured. Without a Messenger’s guidance, man is like a fish out of water. When man abandons this guidance, then his heart is spoiled.