ولا يدفع المزكي زكاته إلى أبيه وجده وإن علا
Translation: The zakat payer does not pay zakat to a father, grandfather or more remote direct ascendants.
Direct ascendants include one’s father and grandfathers as well as mother and grandmothers.
Supporting needy parents through other lawful funds is distinct from using one’s own obligatory zakat to them.