The Quran

Preface

وَلَمّا دَخَلوا مِن حَيثُ أَمَرَهُم أَبوهُم ما كانَ يُغني عَنهُم مِنَ اللَّهِ مِن شَيءٍ إِلّا حاجَةً في نَفسِ يَعقوبَ قَضاها ۚ وَإِنَّهُ لَذو عِلمٍ لِما عَلَّمناهُ وَلٰكِنَّ أَكثَرَ النّاسِ لا يَعلَمونَ

Yusuf Ali

And when they entered in the manner their father had enjoined, it did not profit them in the least against (the plan of) God:¹ It was but a necessity of Jacob?s soul, which he² discharged. For he was, by our instruction, full of knowledge (and experience): but most men know not.³

See the last verse and n. 1730. Though they scrupulously observed their father’s injunctions to the letter, their hearts were not yet pure, and they got into trouble, as the later story will show. They had the hardihood to cast aspersions on Joseph, not knowing that they were in Joseph’s power. And Joseph took a noble revenge by planning a reunion of the whole family and shaming the ten brothers into repentance. He was the instrument for the fulfilment of God’s Plan.
It is a necessity of a Prophet’s soul that he should speak out and teach all that he knows, to the worthy and unworthy alike. This, Jacob did to his unworthy sons, as well as to his worthy sons whom he loved best. It was not for him as a Prophet to guarantee any results. In this case he could not save his Sons from getting into trouble merely because they followed the letter of his advice in a small matter. Apply this to the teaching of one who is greater than Jacob. Men who literally observe some small injunctions of the Holy Prophet Muḥammad and neglect the greater principles which he taught cannot blame him for their troubles and difficulties. If they examined the matter, they would find that they brought the troubles on themselves.
The Prophets of God are full of knowledge?not as men, but as taught by the grace of God, for men, as such, are (as Carlyle said) mostly fools?devoid of knowledge and understanding. (R).