8. Muhammad ibn Yahya has said the following: “Once Muhammad ibn al-Hassan wrote to abu Muhammad (a.s.), and asked about the case of a man who buys goods or a slave-girl in exchange for a certain amount of assets from one who plunders people on the road or from a thief; if it is lawful for him to use the benefits, or fruits thereof or marry the slave-girl which he has bought from a thief or road plunderer. He (the Imam) signed the answer that said, ’Nothing is good in whatever originates from an unlawful source; and using such matters is not lawful.’”