A Sunnat Wazeefah is to recite the following Dua seven times after the Fardh of Fajr and after the Fardh of Maghrib:

ALLAAHUMMA AJIR-NI MINAN NAAR

(O Allah! Save me from the Fire.)

It should be preferably recited while still in the Tashahhud position after the Fardh Salaat. If the person who recited this wazeefah in the morning dies during the course of the day, he will enter Jannat. If he dies during the night after having recited the wazeefah after Maghrib, he will enter Jannat. Thus, reciting it morning and evening, ensures entry into Jannat.