COMMENTARY on 12:89
A. Yusuf Ali:

Translation:
He said: "Know you how you dealt with Joseph 1765 and his brother, not knowing (what you were doing)?"
Commentary:

1765  Joseph now wants to reveal himself and touch their conscience. He had but to remind them of the true facts as to their treatment of their brother Joseph, whom they pretended to have lost. He had by now also learnt from Benjamin what slights and injustice he too had suffered at their hands after Joseph's protection had been removed from him in their home. Had not Joseph himself seen them but too prone to believe the worst of Benjamin and to say the worst of Joseph? But Joseph would be chari table-not only in the sense which they meant when they asked for a charitable grant of grain, but in a far higher sense. He would forgive them and put the most charitable construction on what they did-that they knew not what they were doing!

 

Muhammad Asad:

Translation:
Replied he: "Do you remember 90 what you did to Joseph and his brother when you were still unaware [of right and wrong]?" 91
Commentary:
90  Lit., "know" (see note 81).
91  By coupling his own name with that of Benjamin he possibly hinted at his brothers' early envy and hatred of the two sons of Rachel (cf. verse 8 of this surah and the corresponding note 12); alternatively, the mention of Benjamin may have been due to the readiness with which they accepted the "evidence" of the latter's guilt (verse 77).