Where to get the skill "retribution" to my new companion Hirge

[Monteiro]

Hi, could someone give me a tip on how to get the skill "retribution" to the new cleric companion Hirge?
Probably a "walk in the park" but I'm unable to find it among the choosing set for her.

 

[abstractsense]

Not all of the skills are available to the companions, in particular, they can't learn advanced skills (yet).