Thread by @PhDniX

Today in Arabists say the darnedest things: Fischer claims addressee agreement of the far deixis is no longer productive in pre-classical Arabic. It evidently still is, see Q12:37. Joseph addresses two men with whom he is imprisoned, he is asked to explain their dreams.

He tells them: "I will inform you (dual) of what the interpretation before your food arrives; That (= ḏāli-kumā "that-you:dual) is part of what my lord has taught me."

There is no doubt the form ḏālikumā is chosen OVER ḏālika because the speaker is addressing 2 people.

The Quran in fact attests all 5 possible types of agreement for the masculine singular:
ḏāli-ka 2ms (passim)
(ka-)ḏāli-ki: 2fs (Q19:21) to Maryam, cf. ka-ḏālika (Q19:9) to Zakariyyā.
ḏāli-kum 2mp (passim e.g. Q2:49)
ḏāli-kunna 2fp (Q12:32) to the women of the city

It's not fully attested for the feminine singular and plural but ther's enough to think this system was fully productive in these forms as well. Thus:
FemSg til-ka (passim e.g. Q13:1); til-kumā (Q7:22); til-kum (Q7:43)
MascPl ʔulāʔi-ka (passim); ʔulāʔi-kum (Q4:91; Q54:34)

Crosslinguistically addressee agreement in deictic pronouns is very rare. The only other case that I know of is in Siwi Berber, which @lameensouag wrote about on our now very defunct blog:
orientalberber.wordpress.com/2012/05/29/siw…
See also: lughat.blogspot.com/2014/04/siwi-a…

I completely forgot about this, but was just reminded of it by Lameen's article; There is one Arabic dialect (a very exotic one at that), namely the Yemeni dialect of Jabal Rāziḥ also has addressee agreement, an even more developed system than that of Quranic Arabic.

Interestingly: Peter Behnstedt does not report on the addressee agreement at all. This is perhaps not surprising, he as a man would receive deictics that sound perfectly normal as standard dialectal Arabic: ḏāk, tāk etc.

When Janet Watson started her research she would have been instantly exposed to completely different deictics when talking to her informants: ḏāc, tāc etc. and with her colleague Bonnie Glover Stalls around: ḏākun.
Gender of the researchers must have helped to discovering this!