ẓalla 'to remain' in the Quranic Consonantal Text

In Classical Arabic, the behavior of geminate verbs, that is verbs whose second and third root consonant is the same, is a little different from other verbs. Whenever a CVCV sequence occurs where both Consonants are the same and the second CV stands in an open syllable, the first vowel is syncopated. Hence we get forms like:

*radada > radda'he returned'
*radadū > raddū'they returned'
*radadtu > radadtu'I returned'

For the most part, Quranic Arabic follows exactly this pattern, hence we find:

ظننت /ẓanant/ 'I thought'
ظن /ẓann/ 'he thought'
ظنوا /ẓannū/ 'they thought'

There is, however, one exception in the Quran, namely the verb ظل 'to remain', which, unlike the other verbs of this type does not have two reflexes of the same consonant in the 2sg.m. and 2pl.m. forms:

ظلت /ẓalt/ 'you remained' (Q20:97)
ظلتم /ẓaltum/ 'you (pl.) remained' (Q56:65)

So why is this verb not behaving like every other verb? It turns out that its Classical Arabic cognate shows evidence that this verb is unlike every other verb. The Classical Arabic form of the 2sg.m.  and 2pl.m. is ẓalilta and ẓaliltum, with an i vowel.

This shows that the underlying original verb was, in fact, *ẓalila, not *ẓalala. This however is obscured in the 3sg.m. form ẓalla. Another piece of evidence that points to this verb having an original i vowel in its stem is the imperfect yaẓallu rather than **yaẓullu or *yaẓillu; Verbs with an i stem vowel in the perfect regularly have an a stem vowel in the imperfect. Semantically verbs with an i-stem vowel are semantically stative, which this verb indeed is too.

It therefore seems attractive to interpret ẓalla's exceptional status among the geminate verbs in the Quran as the cause for its anomalous behaviour. We might imagine that in Quranic Arabic a phonetic rule operated that was not active in Classical Arabic:

*VC1iC1C > VC1C

It is quite common for high vowels in Arabic to behave a little different, and be more prone to syncope than a; And this would appear to be an example of that.

There would appear to be one counterexample to the rule as formulated above, namely the internal passive رددت rudidtu'I am brought back' (Q18:36). There are a number of plausible ways to explain this exception, but without further examples, it is impossible to confirm which one is correct.

1. Perhaps the rule only works if the preceding vowel is a, i.e. *aC1iC1C > aC1C
2. Perhaps the rule is simply broken by analogy because the formation of internal passives is productive.
3. Perhaps the rule only functioned on highly sonorous consonants like l, r, n, m

There is one other verb in the Quran that has an original *C1aC2iC2a shape, namely massa'to touch', which in Classical Arabic would have a 1sg. form masistu. However, this form is not attested in a Quran that could help us confirm that its behaviour would be the same.

While this is only a simple example, we see that Quranic Arabic is unlike Classical Arabic, but when it deviates from Classical Arabic, it appears to form a coherent linguistic system on its own.

It is interesting to observe here that the (slightly classicized) forms of ẓaltu and mastu are actually known in the Classical grammatical tradition. Sibawayh makes explicit mention of it:

وأما الذين قالوا: ظلت ومست فشبهوها بلست فأجروها في فعلت مجراها في فعل وكرهوا تحريك اللام فحذفوا

"And as for those that say ẓaltu and mastu, they liken it to lastu ('I am not' from the irregular verb laysa) and they apply it in the faʕiltu form when they conjugate the verb, because they dislike the vowel of the lām (referring to ẓaltu) so they remove it."

Interestingly, Sibawayh in another chapter specifically designates this form as unsual in a chapter dedicated to forms that are unusual (šāḏḏ) in their removal of the vowel, and are irregular (باب ما كان شاذًا مما خففوا على ألسنتهم بمترد), where he says: ومن الشاذ قولهم: أحست ومست وظلت لما كثر في كلامهم كرهوا التضعيف "And it is anomalous to say ʔaḥastu, and mastu and ẓaltu, because it is common in their speech to dislike gemination."

Here we see Sibawayh not outright condemning, but certainly designating as out of the ordinary for correct 'Arabic' the form that we find in Quranic Arabic.