Does disobeying one's father (such as by not scratching his body) affect the acceptance of prayers and fasting?

Filial piety and obedience to parents are obligatory in matters of righteousness, and this is among the greatest acts of drawing near to Allah. Disobeying them is among the greatest of major sins. Obedience to parents is in what benefits them, provided it does not involve disobedience to Allah or harm to the child. Sins and transgressions that do not invalidate prayer and fasting do not nullify acts of worship, but they may diminish their reward.