In Kalabhairavashtakam of Jagadguru Adi Shankaracharya,it is stated
Those who read this enticing octet on Kalabhairava,
Which is the source of eternal knowledge,
Which increases the effect of righteous deeds,
And which destroys grief, passion, poverty, want and anger,
Would surely reach the holy presence of Kalabhairava.
There is no guru greater than Adi Shankaracharya. And if He worshipped Kalabhairava, we must do so as well.