Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
muslim:1382b – [Chain 1] ʿAmr al-Nāqid And Ibn Abū ʿUmar > Sufyān [Chain 2] Ibn al-Muthanná > ʿAbd al-Wahhāb > Yaḥyá b. Saʿīd Bihadhā al-Isnād

" Just as a furance removes impurity," but no mention is made of iron.  

مسلم:١٣٨٢b – وَحَدَّثَنَا عَمْرٌو النَّاقِدُ وَابْنُ أَبِي عُمَرَ قَالاَ حَدَّثَنَا سُفْيَانُ ح وَحَدَّثَنَا ابْنُ الْمُثَنَّى حَدَّثَنَا عَبْدُ الْوَهَّابِ جَمِيعًا

عَنْ يَحْيَى بْنِ سَعِيدٍ بِهَذَا الإِسْنَادِ وَقَالاَ كَمَا يَنْفِي الْكِيرُ الْخَبَثَ لَمْ يَذْكُرَا الْحَدِيدَ