Is it permissible for a father to give to one child and deprive another? And how should we speak with our father, especially since this contradicts Sharia?

All praise is due to Allah.

The text addresses the issue of justice among children in giving gifts, clarifying that it is not permissible to single out some children for a gift while excluding others, except for a legitimate reason. It cites the hadith of Nu'man ibn Bashir, when his father wanted to single him out for a gift, and the Prophet, peace and blessings be upon him, forbade him, saying: "Be mindful of Allah and be just among your children." Whoever has done this must repent and retract their gift, or give the rest of their children a similar gift. An exception to this is when those deprived of the gift agree fully and without coercion, or when there is a legitimate reason such as need, poverty, or seeking knowledge. Children should gently advise their father if he does not treat them justly.