Abbas - Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs
(Saying: Make thou long coats of mail and measure the links (thereof)) the measure of a nail such that it is neither bigger nor smaller than it. (And do ye right) sincerely to Him. (Lo! I am Seer) Aware (of what ye do) of good or evil.
And We said: ‘Fashion, from it, long coats of mail — complete suits of armour which the person wearing it drags behind him along the ground — and measure [well] the links’, that is, in the weaving of the coats (the maker of these is called sarrād). In other words, make them so that the rings thereof are arranged properly. And act, O family of David, together with him, righteously. Indeed I am Seer of what you do, and will requite you for it accordingly.
Here Allah tells us how He blessed His servant and Messenger Dawud (David), peace be upon him, and what He gave him of His great bounty, giving him both prophethood and kingship, and huge numbers of troops. And He blessed him with a mighty voice. Such that when he glorified Allah, the firm, solid, high mountains joined him in glorifying Allah, and the free-roaming birds, who go out in the morning and come back in the evening, stopped for him, and he was able to speak all languages. In the Sahih it is recorded that the Messenger of Allah heard the voice of Abu Musa Al-Ash`ari, may Allah be pleased with him, reciting at night, and he stopped and listened to his recitation, then he said:
(This man has been given one of the sweet melodious voices of the Prophet Dawud.) Abu `Uthman An-Nahdi said, "I never heard any cymbal, stringed instrument or chord that was more beautiful than the voice of Abu Musa Al-Ash`ari, may Allah be pleased with him.''
(Glorify) means, glorify Allah. This was the view of Ibn `Abbas, Mujahid and others. The root of this word Ta'wib means to repeat or respond, so the mountains and birds were commanded to repeat after him.
وَأَلَنَّا لَهُ الْحَدِيدَ
And We made the iron soft for him. Al-Hلasan Al-Basلri, Qata0dah, Al-A mash and others said, He did not need to heat it in the fire or beat it with a hammer؛ he could simply twist it in his hands, like a thread. Alla0h said:
أَنِ اعْمَلْ سَـبِغَـتٍ
Saying: Make you perfect coats of mail..., which means chain mail. Qata0dah said, He was the first person ever to make chain mail؛ before that, they used to wear plated armor.
وَقَدِّرْ فِى السَّرْدِ
(and 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 فِى السَّرْدِ
(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.''
and work you (men) righteousness. means, with regard to what Alla0h has given you of blessings.
إِنِّى بِمَا تَعْمَلُونَ بَصِيرٌ
Truly, 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.
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
This is an allusion to the countless favors with which Allah had blessed the Prophet David. He was an ordinary young man of the tribe of Judah, living at Bethlehem. In a campaign against the Philistines he slew the giant Goliath, the great enemy of Israel, and suddenly grew in esteem of the Israelites. With this event began his rise to prominence; so much so that after the death of Saul he was first elected king of Judah in Hebron (mod. AI-Khalid, and then a few years later he was made king over all the tribes of Israel. He took Jerusalem and made it the capital of the kingdom of Israel. It was under his leadership that for the first time in history a God-worshiping kingdom was established, whose boundaries extended from the Gulf of `Aqabah to the western banks of the River Euphrates. In addition to these favors, he was further graced with Divine bounties in the form of knowledge and wisdom, and the qualities of justice and mercy and devotion to the truth. (For details, see E.N. 273 of Al-Baqarah and E.N. 7 of Bani Isra'il).
For this please refer to AI-Anbiya': 79 and E.N. 71 thereof.
For this also please refer to AI-Anbiya': 80 and E.N. 72 thereof.