The Woman Who Is Examined - 60:4
"There is a good example for you in Abraham and those who were with him. Those who were with him said to their people, "We are far from you and those whom you serve besides Allah. We do not know you. There is eternal enmity and hatred between us and you until you believe in Allah ALONE. Except that Abraham´s words to his father, "I will pray for your forgiveness, but I cannot protect you against anything from Allah"(as a mistake). "Our Lord, to You we trust, to You we turn, and to You we shall return."
We cannot ask forgiveness for those who associate partners, even if they are relatives:
The Repentance/9:113
Neither the Messenger nor the believers, even if they are relatives, can ask forgiveness for those who associate partners after it has become clear to them that they are the people of Hell.