Paladin tank "concentration"

SORRY FOR BAD ENGLISH
i am a lvl 43 pala tank, on the istances, my group ask to get "congentration buff ", a day a man say me is in spellbook in holy sesson page 3, but i cant fint it! what is it? where i can find it?
my groups say me its essential for tanking, but i cand find it!
help me PLEASE
i am a lvl 43 pala tank, on the istances, my group ask to get "congentration buff ", a day a man say me is in spellbook in holy sesson page 3, but i cant fint it! what is it? where i can find it?
my groups say me its essential for tanking, but i cand find it!
help me PLEASE