Source / Evidence
Quran 22:73. The verse presents an explicit challenge (tahaddī): 'Indeed, those you invoke besides Allah will never create [as much as] a fly, even if they gathered together for that purpose. And if the fly should steal away from them a [tiny] thing, they could not recover it from him. Weak are the pursuer and pursued.' The challenge has two parts: (1) collective creation of even a fly is beyond all created beings, and (2) even recovering what a fly takes is beyond them. Both remain true 1,400+ years later. Modern biomimicry and synthetic biology (Cyborg beetle 2006, RoboBee 2013, Festo's BionicOpter 2014) have produced flying micro-robots, but none replicates a living fly's integrated sensory, propulsion, and reproductive systems at that scale.
Classical tafsir
Al-Tabari, Ibn Kathir, and al-Qurtubi all read this verse as a burhan (proof) of tawhid: if collective created power cannot match a single fly, how could it match the Creator? Al-Razi notes the specific word 'ذباب' (dhabab, fly) — not a large creature, not a celestial body, the smallest possible target for the challenge, which makes the impossibility claim sharper, not weaker.
Limits of the statement
The challenge is rhetorical and theological, not a research-program disproof. Humans have built impressive fly-like devices and even genetically modified flies, which is itself remarkable — but no collective effort has produced a living fly from non-living matter, and no creator has recovered what a fly has taken. The verse's claim holds in the same register it was issued: as a sign (ayah) of divine uniqueness, not a science-fair rule.