Understanding The Prophet's Life
From Issue: 515 [Read full issue]
Muslim in his Sahih reports on the authority of Mamar ibn Abdallah that the Prophet, on him be peace, said: "Only the misguided hoard." For the hoarder is one who buys up food which people need and keeps it in store with the intention of putting up the price. He is an oppressor of the buying public. Therefore the authorities are entitled to compel people to sell their stocks for fair value when they are urgently needed.
So, for instance, if someone has food he does not need while people are starving he may be forced to sell it to them for fair value. This is why the jurists hold that he who is in urgent need of another's food may take it from him, regardless of his wishes, for fair value. Were he reluctant to sell except for more than the regular price he would still be entitled only to this regular price.
"Public Duties in Islam" - Ibn Taymiya, pp. 32-33