It depends on who you are and who you say it to. I would not say such things to most people. It would be absolutely wrong to do so. But I would say it to a person who had been practicing hard and had gotten some results from his practice. Before saying anything, however, I would make sure his view, or understanding, is correct. If a student is practicing hard, but with the idea that he is becoming enlightened, and his teacher says, "Yes! Yes, you're correct! You should try to become enlightened, reach Nirvana and become a Buddha, " the student's practice will be ruined. It would be an evil thing to do.
A phrase may help or hurt, depending on the person and the condition he is in. Let me ask you a question: Do you believe there is a Buddha, or do you prostrate just for the exercise? If you believe that there really is a Buddha, and you practice so that you can become a Buddha, and you prostrate in order to appease the Buddha because you rely completely on him, then you are in for trouble.
This stanza mentions two stories from Buddhist scripture. The first illustrates that if your view is correct, then you are instantly enlightened. In the Lotus Sutra there is a story of an eight year old naga maiden who became a Buddha. A naga is a dragon, not a human being. According to the Hinayana tradition, it is impossible for anyone to become a Buddha who is not male, an adult, and human. You must cultivate practice for three asamkhya kalpas (one asamkhya kalpa is billions of years). When your karma ripens, you will be born as a human male, and as an adult you may attain enlightenment through practice. It seems that the naga maiden had three strikes against her.
Once, she was attending Sakyamuni Buddha, and she offered him her pearl necklace. The maiden turned to Sariputra, an arhat and disciple of the Buddha, and asked, "What do you think, Sariputra, is this an easy thing to do?"
Sariputra answered, "Yes, it is easy."
Then the dragon maiden said, "Becoming a Buddha is as easy as this." In that instant, she became a Buddha in a distant realm of the universe.