Is it permissible to trade in train tickets and sell them for a price higher than their original value, and is there a sin upon one who sells his ticket for its purchase price if he knows that the buyer will resell it for a higher price?

The basic principle concerning buying and selling is permissibility, based on the Almighty's saying: (And Allah has permitted trade and forbidden interest). However, it is forbidden to sell subsidized goods allocated for consumption to those who trade in them, because this defeats the purpose of government support, harms those in need, increases prices, and violates the instructions of the ruler. Therefore, it is not permissible to trade in subsidized train tickets. Whoever buys a ticket must use it themselves or sell it at its original price to someone who truly needs it. It is not permissible to sell it for more than its price, or to sell it to someone known to be trading in it, because that falls under cooperation in sin and aggression. However, if a person is forced to buy it at a higher price from traders, there is no blame on them; the sin falls upon the seller.