Musannaf Ibn Abi Shaybah

Hazrat Ata (may Allah have mercy on him) disliked the sale of the goldsmith's clay (the clay of the jeweler).

Hazrat Hasan (may Allah be pleased with him) disliked the sale of goldsmith’s dust, except that gold dust be sold with silver and silver dust be sold with gold.

Hazrat Muhammad bin Abu Ja'd says that I asked Hazrat Sha'bi (may Allah have mercy on him) about buying the clay of a goldsmith. He disliked its sale and said, "This is deception." Hazrat Muhammad (may Allah have mercy on him) says, "My father used to sell it in exchange for something present (i.e., hand to hand sale)."

Ibrahim says, there is no harm in selling gold dust for silver and selling silver dust for gold.