Speak to Duthorian Rall in Stormwind.
I greet you once again, [player]. I am more proud to call you $g brother:sister; than ever before--your dedication is a tribute to us all.
The time has come for me to bestow a great gift upon you. But know this, for now I give you this freely, but later, when time permits, this will be a much greater challenge to all paladins who choose to undertake my quest.
Speak to me again and I shall grant you a great boon.