Mukhtasar Muslim (Abridged) 909 — Prohibition of selling wheat before

It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: Whoever buys grain should not sell it until he has taken possession of it. Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: I consider this to apply to everything.