Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates that the Prophet Muhammad (peace and blessings be upon him) said: "Whoever buys grain should not sell it further until he has taken possession of it." Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) says: I think that the ruling for everything is like that of grain. (Imam Ibn Hibban, may Allah have mercy on him, says:) Amr bin Dinar heard this narration from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both), and he also heard this narration from Tawus on the authority of Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both), so both chains are preserved.