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
bayhaqi:10526 – Abū Saʿīd > Abū al-ʿAbbās > al-Rabīʿ > al-Shāfiʿī > Ibn ʿUlayyah Shak al-Rabīʿ > Salamah b. ʿAlqamah > Muḥammad b. Sīrīn > Suʾil > al-Ḥadīd Bi-al-Ḥadīd

[Machine] Allah knows best, but it seems they were trading shields with one another.  

البيهقي:١٠٥٢٦ – وَأَخْبَرَنَا أَبُو سَعِيدٍ ثنا أَبُو الْعَبَّاسِ أنا الرَّبِيعُ أنا الشَّافِعِيُّ أنا ابْنُ عُلَيَّةَ إِنْ شَاءَ اللهُ شَكَّ الرَّبِيعُ عَنْ سَلَمَةَ بْنِ عَلْقَمَةَ عَنْ مُحَمَّدِ بْنِ سِيرِينَ أَنَّهُ سُئِلَ عَنِ الْحَدِيدِ بِالْحَدِيدِ فَقَالَ

اللهُ أَعْلَمُ أَمَّا هُمْ فَكَانُوا يَتَبَايَعُونَ الدِّرْعَ بِالْأَدْرُعِ