How to write CanCanCan Ability for user to read only their data?

How do you restrict user access so a user can only read their own record?

I've tried:

def initialize(user)
  can :read, User, :id => user.id

and this:

def initialize(user)
  can :read, user

but I can still access every user in index and show. I have authorize_resource in the UsersController.

Relevant documentation for reference:https://github.com/CanCanCommunity/cancancan/wiki/Defining-Abilities

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