Praise be to Allaah.
It is not permissible to sell them because when Allaah forbids a thing He also forbids its price. Ibn ‘Abbaas (may Allaah be pleased with them both) said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) said: ‘Allaah has cursed the Jews because fat was forbidden to them, but they sold it and took its price. When Allaah forbids something he also forbids its price.’” (Reported by Imaam Ahmad, 2546).
With regard to doubtful things, it is better not to sell them, so as to be free of any blame, as the Prophet (peace and blessings of Allaah be upon him) said. Al-Nu’maan ibn Basheer said: “I heard him saying, ‘I heard the Messenger of Allaah (peace and blessings of Allaah be upon him) say: “What is permitted is clear and what is prohibited is clear, and between them are doubtful things which many people do not know about. Whoever avoids doubtful things will be on the safe side with regard to his religion and his honour, but whoever falls into doubtful things will fall into haraam things.”’” (Reported by Muslim, 2996). And Allaah is the Source of Strength
Sheikh Muhammed Salih Al-Munajjid