Translation of the verse 2 from Surah Al-‘adiyat : Number of verses 11 - - page 599 - Part 30.
Striking sparks of fire (by their hooves),
And the producers of sparks [when] striking
(100:2) then raise sparks of fire (by their hoofs), *2
*2) "Dashing off sparks" indicates that the horses run in the dead of night, for the sparks struck by their hoofs become conspicuous only at night.
Source : Al-‘adiyat Verse 2: And the producers of sparks [when] striking