To take a customary action to ward off some misfortune that is believed to be attracted by a presumptuous statement.
Hopefully; a self-directive to undertake the customary action to ward off bad luck.
To caution or admonish (someone) against unwise or unacceptable behaviour.
To notify or inform (someone, about something).
To give warning.
To summon (someone) to or inform of a formal meeting or duty.
To advise or order to go or stay away.
To make (someone) aware of impending danger, evil, etc.