وَفَرْضُ الْغُسْلِ: الْمَضْمَضَةُ، وَالِاسْتِنْشَاقُ، وَغَسْلُ سَائِرِ الْبَدَنِ.
Translation: The obligations of ghusl are rinsing the mouth, drawing water into the nose, and washing all the rest of the body.
These three are separately required; merely pouring water over the visible body does not automatically fulfill rinsing of the mouth and nose.