Is it permissible for a father to withhold his son's money, which the latter earned through his own work, under the pretext that he is foolish, knowing that the father has covered the expenses of his other children?

The son has the right to demand his debt from his father if the father is solvent. However, it is preferable to be patient with him, unless the delay causes harm to the son. This applies if the son is of sound judgment. If the son is foolish, then the ruler is the one who places him under interdiction. The father must be equitable among his children in gifts, but not in expenses. The son must honor his father and be kind to him, regardless of his condition, for the father's right is great, and honoring him is among the best acts of closeness [to Allah].