Tafsir of Yusuf 12:79

{معاذ الله} (I seek refuge in Allah): This is a directed speech.

• Its apparent meaning: According to the logic of your own verdict, it is mandatory to seize the one in whose saddlebag the cup was found and to enslave him. If we were to seize someone else, it would be an injustice according to your own school of thought. Why, then, do you request what you know to be an injustice?
• Its inner meaning: Allah has commanded me and revealed to me that I should take Benjamin and detain him for a benefit—or numerous benefits—that He knows in this matter. If I were to take someone other than the one He commanded me to take, I would be an oppressor and acting in opposition to revelation.

The meaning of {معاذ الله أن نأخذ} (I seek refuge in Allah that we should take) is: "We seek refuge in Allah—a refuge—from taking." The verbal noun (ma‘ādh) is annexed to the object, and the preposition (min) is omitted.

{إذاً} (Then/In that case) is a response and a consequence to them, because the meaning is: "If we were to take someone else in his place, we would be oppressors."

{فلما استيأسوا منه خلصوا نجيا قال كبيرهم ألم تعلموا أن أباكم قد أخذ عليكم موثقا من الله ومن قبل ما فرطتم فى يوسف فلن أبرح الا رض حتى يأذن لى أبى أو يحكم الله لى وهو خير الحاكمين}

(So when they despaired of him, they went off to confer privately. Their eldest said, "Do you not know that your father has taken a pledge from you by Allah, and how you failed regarding Yusuf before? Therefore, I will never leave this land until my father permits me or Allah decides for me, and He is the best of judges.")