What is the ruling if one states, 'O adulterer, son of an adulterer'?

Primary text

The statement 'O adulterer, son of an adulterer' (Ya zani ibn az-zani) constitutes two distinct acts of slander against the father and the mother. If the father is alive, each individual (the father and the mother, presuming the mother is also alive or the slander is directed at her status) is entitled to the Hadd penalty. If the father is deceased, the apparent established ruling in the Madhhab is that the Hadd penalty is not incurred for slandering the deceased father.