This quest is not available in game.
Speak to Duthorian Rall in Stormwind.
Greetings, brother. Duthorian Rall, one of our most influential paladins, was speaking about you recently. I overheard him talking about how it was time you be put to the test some... along with some very complimentary things about how well you've performed thus far.
If I were you, I'd head to Stormwind and speak to him when you have time. I'm sure he's in the Cathedral of Light--that's where he spends most of his time.