Musnad Ahmad 907:181

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Simak, who said: I heard Jabir ibn Samurah saying: I heard the Prophet of Allah, peace and blessings of Allah be upon him, saying: "The treasures of Chosroes, the white one, shall certainly be opened." Shu'bah said: Or he said, "That which is in the white one, by a group of the Muslims."