What is the ruling on the sin incurred by someone who institutes a bad practice (sunnah sayyiah) and others act upon it? And can this bad practice be forgiven? And what is the ruling on a father who raises his children religiously but they later stray from the religion?

Whoever calls to disobedience bears the sin of those who commit it, as stated in the Hadith (definition): «Whoever introduces a bad practice in Islam will bear its sin and the sin of those who act upon it after him.» However, sincere repentance erases what came before it, so the repentant person does not bear the sin of those who followed him after his repentance. This is understood to apply to those who have not repented from that sin. And if a father raises his child well and then the child becomes corrupt, there is no sin upon the father.