A. Yusuf Ali:Translation:
And when they entered in the manner their father
had enjoined, it did not profit them in the least against
(the plan of) Allah: 1731 It was but a necessity of
Jacob´s soul, which he 1732 discharged. For he was,
by our instruction, full of knowledge (and experience):
but most men know not. 1733

Muhammad Asad:Translation:
But although 66 they entered [Joseph's city] in the way their father had bidden them, this proved of no avail whatever to them against [the plan of] God 67 [His request] had served only to satisfy Jacob's heartfelt desire [to protect them]: 68 for, behold, thanks to what We had imparted unto him, he was indeed endowed with the knowledge [that God's will must always prevail 69 ]; but most people know it not.
1731 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 Allah's Plan.
1732 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 Muhammad 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.
1733 The Prophets of Allah are full of knowledge—not as men, but as taught by the grace of Allah, for men, as such, are (as Carlyle said) mostly fools—devoid of knowledge and understanding. (R).