The "but (fa-)" at the beginning of the phrase indicates that they kindled the fire for light and it lit up [all round them] and they felt confident at this. But they were immediately overcome by frustration and disappointment. How powerfully effective is this being thwarted at the very moment of success! The light being taken away in the [consequence - that is, second half - of the] conditional sentence is apparently necessitated by the illumination [but the necessity of this is not obvious]. The necessity being hidden indicates the existence of implied [sentences], as follows:

When all was lit up around them they busied themselves with the light yet did not preserve it. They did not give it due importance and were not aware of its value. They did not keep [the fire] alight and it went out. For being preoccupied with the result, they neglected the means. As inferred by the verse "But man doth transgress all bounds, * In that he looks upon himself as self-sufficient (inna'l-insana la-yatghâ; An râhu'staghnâ),"(96:6-7) [their preoccupation with the light] was the cause of its ceasing and being extinguished, as though the very illumination caused the light to vanish.

As for the phrase "and leaves them in utter darkness (wa tarakahum fi zulumâtin)," having pointed out how they lost the bounty of the light, [the Qur'an] describes their disappointment at the calamity of being plunged into darkness.

The phrase "[wherein] they cannot see (Iâ yubsirûn):" know that when darkness falls and a person loses his way, he may stop and be consoled by the sight of his companions and possessions. But if he does not see them, stopping may be as bad for him as moving on, or even worse.

The phrase "Deaf, dumb, blind - and they cannot turn back. (Summun bukmun 'umyun fa-hum lâ yarji'ûn):" when a person is overcome by such a calamity, he finds solace by hoping for salvation and seeking it from four successive directions:

Firstly he hopes to hear the cries of nearby villagers or other travellers and [anticipates] that if he calls for help they will save him. But since the night is soundless and silent, he is no different to a deaf man, so [the Qur'an] calls him "deaf" and that hope is lost.

Secondly he hopes that if he shouts or calls out for help there is the possibility that someone will hear and come to his aid. But when the night is deaf and dumb, there is no difference between the speaker and someone dumb, so [the Qur'an] calls [him] "dumb," silencing him and destroying that hope too.

Thirdly he hopes to be saved by espying some sign or a fire or light that will show him the way to his destination. But when the night is overwhelmingly ashen-black, frowning and blind, the seeing and the blind are the same, so [the Qur'an] calls [him] "blind" extinguishing that hope too.