Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates: The Prophet (peace and blessings be upon him) said: "Surah al-Hadid was revealed on a Tuesday, and Allah Almighty created iron on a Tuesday." The complete narration has already passed earlier, in the Book of Medicine, in the chapter on cupping.
Al-Tabarani recorded it; its chain contains a narrator, Maslamah bin Ali, who is da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب التفسير / 11401