What is the reason for the glorification of filial piety in religion? Is it due to upbringing and financial support, or are there other reasons, especially if the father differentiates between his children in giving?

The Shari'a has made it obligatory to honor one's parents, treat them kindly, and obey them. Among the most important reasons for this are their upbringing of the child, their toil for him, and their care for him, as they are the cause of his existence. Allah has linked His right with their right. Even if the father is unfair in giving and does not act justly, this does not absolve the child from honoring him. The child must honor and maintain ties with his parents. The father may have a justification for not equalizing, and the child should supplicate and advise with kindness.