"Berber" language in early Arabic texts

Searching Shamela, I recently realised that the earliest references to a language of (al-)Barbar in Arabic go back further than I had assumed, to the second century AH. While these are unlikely to shed much light on actual linguistic practices, they are worth a look.

Two occur in the Qur'ānic commentary (tafsīr) of Mujāhid ibn Sulaymān (d. 150 AH = 767 AD); one in his discussion of sūrat al-Isrā':

فقال عبد الله بن الزبعري السهمي: إن الزقوم بلسان بربر التمر والزبد. قال أبو الجهل: يا جارية ابغنا «٣» تمرا فجاءته. فقال لقريش وهم حوله تزقموا من هذا الزقوم الذي يخوفكم به محمد «٤» .
And ʕAbd Allāh ibn al-Zabʕarī al-Sahmī said: Zaqqūm means 'date' and 'butter' in the tongue of Barbar. Abū Jahl said "Slave-girl, find us some dates", and she came to him, and he said to Quraysh as they were about him: "Have some of this zaqqūm that Muhammad is scaring you with".

And one, almost identical, in his discussion of sūrat al-Dukhān:

بلسان بربر وأفريقية الزقوم يعنون التمر والزبد، زعم ذلك عبد الله بن الزبعري السهمي، وذلك أن أبا جهل قال لهم: إن محمدا يزعم أن النار تنهت الشجر وإنما النار تأكل الشجر، فما الزقوم عندكم؟ فقال عبد الله بن الزبعري: التمر والزبد. فقال أبو جهل بن هشام: يا جارية، ابغنا تمرا وزيدا. فقال: تزقموا.
In the tongue of Barbar and Ifrīqiyah, zaqqūm they mean 'date' and 'butter'. So claimed ʕAbd Allāh ibn al-Zabʕarī al-Sahmī, on the basis that Abū Jahl said to them "Muhammad claims that the Fire grows trees, yet fire consumes trees! So what is zaqqūm according to you?" And ʕAbd Allāh ibn al-Zabʕarī said: "Dates and butter". And Abū Jahl ibn Hishām said: "Slave-girl, find us some dates and butter!" And he said: "Have some zaqqūm."

One is vaguely reminded of Siwi a-zəggar "a (single) date"; but if indeed this were a word of "Barbar and Ifrīqiyah", one would hardly expect it to trip from the lips of Abū Jahl, and still less to be familiar to his audience. (For those unfamiliar with the context: Abū Jahl was the foremost enemy of early Islam, and ʕAbd Allāh ibn al-Zabʕarī was an anti-Islamic poet; their assertion that in some foreign language zaqqūm means "dates and butter" was almost certainly intended as mockery of the Qur'ān, not as serious lexicography.) The juxtaposition of "Barbar and Ifrīqiyah", however, seems to corroborate that the intended reference is indeed to the Berbers rather than to any East African groups.

Another is to be found in the earliest Arabic dictionary - the Kitāb al-ʕAyn, by al-Khalīl ibn Aḥmad:

والقَيطونُ: المخدع في لغة البربر ومصر.
qayṭūn: chamber, in the language of the Barbar and Egypt.

The ultimate origin of this word, unlike that of zaqqūm, is perfectly clear: it comes from Greek κοιτών, probably via Aramaic. The term is used in Coptic too: ⲕⲟⲓⲧⲱⲛ. In modern Berber varieties its form (e.g. aqiḍun) has a q, suggesting a more recent borrowing from Arabic, but one may reasonably suspect that Berbers in Cyrenaica and the Western Desert (most of whom have since switched to Arabic) would have been familiar with some version of the Greek term before Arabic influence.

A number of references to the "Barbar" are to be found in the works of Imām Mālik ibn Anas. None of these refer to the language, but one, in al-Mudawwanah, makes a clear reference to skin colour in the context of what counts as a legally punishable insult, confirming (unless this was a later scribe's addition) that the term's reference was indeed to North rather than (as Rouighi's hypothesis might suggest) East Africa:

بَلَغَنِي أَنَّ مَالِكًا قَالَ فِي الْمَوَالِي كُلِّهِمْ: مَنْ قَالَ لِبَرْبَرِيٍّ يَا فَارِسِيُّ أَوْ يَا رُومِيُّ أَوْ يَا نَبَطِيُّ أَوْ دَعَاهُ بِغَيْرِ جِنْسِهِ مِنْ الْبِيضِ كُلِّهِمْ فَلَا حَدَّ عَلَيْهِ فِيهِ، أَوْ قَالَ يَا بَرْبَرِيُّ وَهُوَ حَبَشِيٌّ فَلَا حَدَّ عَلَيْهِ وَهُوَ قَوْلُ مَالِكٍ.
It has reached me that Mālik said of mawlās in general: "Whoever says to a Berber 'Hey, Persian!' or 'Hey Roman!' or 'Hey Nabaṭī!', or calls him by any other nation of the whites - he is not to be punished for it. Or if he says 'Hey Berber!' when he is really Ethiopian, he is not to be punished for it. That is Mālik's statement.