1)
Why will he praise Hashem among the nations?
1.
Radak: It is because He saved him from men of violence, and elevated him over his enemies and gave him vengeance against them.
2.
Malbim (Tehilim 18:50): It is to thank Him for the good.
2)
Among which nations will he praise Hashem?
1.
Radak: In front of every nation.
2.
Radak (Tehilim 18:50): In front of the nations that heed me and serve me.
