Is the money that the questioner's grandfather obtained from selling a portion of land they owned (unlawfully), and which exceeds the amount of the trust (amanah) he deposited with the questioner's deceased father, considered a receipt of the trust by him, thereby absolving the father's liability?

Assets written by a father in the name of his children are considered inheritance if the intention was to disinherit some heirs or if the gift did not meet its legal conditions. These assets must be divided according to the Islamic legal distribution (Shar'i division), and the grandfather must be given his due share. It is not permissible to withhold money that the grandfather entrusted to the father as a deposit, unless the grandfather unjustly took from the children's money; in that case, they may take an amount equivalent to their right and return the remainder to him. This is known as the issue of al-zafar.