Contacts being pulled from old Apple id

I am trying to set up an older iPad that I no longer use for my dad. I created an Apple id for him and logged out of iCloud (I had been logged in on the iPad I plan to give to him with my Apple id). Then I logged in to iCloud on that same iPad with the newly created Apple id. However, if I look at his contacts, it still lists all of my contacts. How can I fix this? Thanks.