“Mathaluhum ka-mathali alladhī istawqada nāran”
“Their likeness is like that of one who kindled a fire.” (al-Baqarah 2:17, excerpt)
“Dhahaba Allāhu bi-nūrihim”
“God took away their light.” (al-Baqarah 2:17, excerpt)
The simile uses the singular relative “alladhī” for an imagined person, then turns to the plural pronoun in “nūrihim.” The singular picture supplies a vivid model for the condition of a group; the plural returns to those being described.
There is no contradiction of number. The discourse has two related referents: the single figure within the parable and the actual group whose situation the parable illustrates.