5.3 Service (Rule 13)

Service is the act of putting the ball into play by the right back-row player, who hits the ball with one hand or any part of the arm from the service zone (Rule 13.1). The server must hit the ball within 8 seconds after the first referee's whistle for service (Rule 13.2.1).

Source: Rule 13.1, Rule 13.2.1, Rule 13.2.2, Rule 13.2.3

Send this to your friend — argument over.