I heard about a Hadith (3 types of people that will be saved from hellfire) according to which
praying 4 rakat before Duhr and 4 rakat after Duhr makes Jahannam fire Haram for a person's body (skin).
How do we pray these 4 rakats?
For example in Hanafi school Duhr consists of: 4 rakat Sunnah, 4 rakat Fard and 2 rakat Sunnah => total 10 rakat. Does the Hadith mean we must pray 4+10+4=18 rakats.
And what do we say as niyyat?