What is the ruling on my brother selling airline tickets given to him and his family—which cannot be exchanged for cash and have a limited validity period—for seventy percent of their value, given his inability to travel due to war conditions? And is it permissible for him to dispose of them by selling them or giving them to his relatives?

The ruling on selling free travel tickets depends on the conditions set by the granting entity. If the entity stipulates that the recipient is not entitled to their value, then it is not permissible to sell them, based on the Prophet's (peace be upon him) saying: "Muslims are bound by their conditions, except for a condition that makes a forbidden thing lawful or a lawful thing forbidden." However, if no such condition is stipulated and the tickets are given as an unconditional gift, then the recipient may sell them, benefit from their price, or give them away, because they have become his property, and he may dispose of them like any other of his possessions.