đā-li- masculine singular ti-l- feminine singular đāni- masculine dual tāni- feminine dual 'ulā'i- masculine/feminine animate plural
The second bit agrees with the addressee:
-ka masculine/feminine singular -kumā masculine/feminine dual -kum masculine plural -kunna feminine animate plural
(In modern standard Arabic, only -ka is normally used here; even in Qur'anic contexts, the other forms' usage seems to be limited.)
Thus in Surat Yusuf, verse 32, Pharaoh's wife, addressing her women friends, says:
فَذَلِكُنَّ الَّذِي لُمْتُنَّنِي فِيهِ
fa-đālikunna llađī lumtunnanī fīhi
That is the man about whom you blamed me!
Then in verse 37, Yūsuf/Joseph, addressing his two cellmates, says:
ذَلِكُمَا مِمَّا عَلَّمَنِي رَبِّي
đālikumā mimmā `allamanī rabbī
That is (part) of what my Lord has taught me.
Likewise, in Surat al-A`rāf 22, God tells Adam and Eve:
أَلَمْ أَنْهَكُمَا عَن تِلْكُمَا الشَّجَرَةِ
'a-lam 'anhākumā `an tilkumā ššajarati?
Did I not forbid you from that tree?
It's not hard to come up with a story for how this grammatical phenomenon could have emerged: li in Arabic means "to" or "for", and the endings it takes are (with one exception) the same as those above, so it could easily have either conveyed a presentative meaning (compare English expressions like "That's London for you!") or, less probably in this case, indicated proximity to the addressee ("Get me that book next to you"). But I have a question for all you wonderful readers who have gotten this far: do you know of any other language that does something like this?