Al-Hadid ('Iron'), 29 Medinan verses, opens with the glorification of God, the First and the Last, the Outward and the Inward (57:3). It urges the believers to spend in God's cause and lend Him 'a goodly loan,' and notes that iron was sent down 'in which is great might and benefits for people' (57:25). Classical exegetes read the surah's address to those who believe yet fall short in generosity as directed at the early Medinan community still adjusting to organised almsgiving, and its rhetorical question, 'what is with you that you do not spend in the cause of God' (57:10), is regularly paired in later homiletic literature with its statement that iron was 'sent down' with both military and civil benefit (57:25), a verse some modern apologetic writers read alongside the cosmic origin of heavy elements in stellar nucleosynthesis, a reading absent from the classical commentary tradition, which understood 'sent down' in the ordinary sense the Quran uses for any divinely provided benefit.
Al-Hadid opens the run of surahs classical compilers grouped as al-musabbihat, those beginning with a form of the verb 'to glorify,' a small cluster (including Al-Hashr, As-Saff, Al-Jumua and At-Taghabun, all read in this same portion) that later devotional literature recommended reciting together, particularly before sleep, on the strength of hadith describing the Prophet's own habit of doing so. The surah's image of a wall separating believers with light from hypocrites left in darkness on the Day of Judgement (57:13) supplied later Islamic eschatological writing with one of its most vivid single images of spiritual separation.