أَنِ اعْمَلْ سَابِغَاتٍSaying:Make you perfect coats of mail...,which means chain mail.Qatadah said,He was the first person ever to make chain mail; before that, they used to wear plated armor.وَقَدِّرْ فِي السَّرْدِand balance well the rings of chain armor (Sard),This is how Allah taught His Prophet Dawud, peace be upon him, to make coats of mail.Mujahid said concerning the Ayah:وَقَدِّرْ فِي السَّرْد (and balance well the rings of chain armor (Sard)),"Do not make the rivets too loose that the rings (of chain mail) will shake, or make them too tight that they will not be able to move at all, but make it just right."Ali bin Abi Talhah reported that Ibn Abbas said,"Sard refers to a ring of iron."Some of them said,"Chain mail is called Masrud; if it is held together with rivets."وَاعْمَلُوا صَالِحًاand work you (men) righteousness.means, with regard to what Allah has given you of blessings.إِنِّي بِمَا تَعْمَلُونَ بَصِيرٌTruly, I am All-Seer of what you do.means, watching you and seeing all that you do and say؛ nothing of that is hidden at all