In those days, the prophets of David (Dawud in arabic) often faced wars. They used to use heavy armor so they were unable to move freely. Then came the command of Allah Almighty that the Prophet David as to make armor out of iron as He said:
۞ وَلَقَدْ ءَاتَيْنَا دَاوُۥدَ مِنَّا فَضْلًۭا ۖ يَـٰجِبَالُ أَوِّبِى مَعَهُۥ وَٱلطَّيْرَ ۖ وَأَلَنَّا لَهُ ٱلْحَدِيدَ ١٠
أَنِ ٱعْمَلْ سَـٰبِغَـٰتٍۢ وَقَدِّرْ فِى ٱلسَّرْدِ ۖ وَٱعْمَلُوا۟ صَـٰلِحًا ۖ إِنِّى بِمَا تَعْمَلُونَ بَصِيرٌۭ ١١
“Indeed, We granted David a ˹great˺ privilege from Us, ˹commanding:˺ “O mountains! Echo his hymns! And the birds as well.” We made iron mouldable for him. (10) instructing: “Make full-length armor, ˹perfectly˺ balancing the links. And work righteousness ˹O family of David!˺. Indeed, I am All-Seeing of what you do.” (11)” (QS. Saba’ : 10-11).
Many argue about the interpretation of the verse “and we softened the iron for him.”
The most widely accepted opinion is that Dawud has found a way to soften iron by melting it with fire so that hard iron can be formed to his liking.
The intelligence of the Prophet David is also evident from his armor consisting of iron spheres so that the wearer can move freely and be protected from enemy swords, axes, and daggers.
The armor of the Prophet David was the best work of armor that existed at that time. Meanwhile, the enemy’s battle armor, in addition to being heavy, cannot move freely, it can also still be penetrated by the enemy’s sword.
Since using David’s armor, the soldiers of the Prophet David have always won wars, of course, with the help of Allah Almighty as well.