قال لن أرسله معكم حتى توتون موثقا من الله
He (Yaqub (Jacob)) said: "I will not send him with you until you swear a solemn oath to me in Allah's Name...''),
until you swear by Allah with the strongest oath,
لتٲتنني به إﻻ أن يحاط بكم
that you will bring him back to me unless you are yourselves surrounded (by enemies),
unless you were all overwhelmed and were unable to rescue him,
فلما آتوه موثقهم
And when they had sworn their solemn oath,
he affirmed it further, saying,
قال الله على ما نقول وكيل
he said: "Allah is the Witness to what we have said."
Ibn Ishaq commented,
"Yaqub did that because he had no choice but to send them to bring necessary food supplies for their survival. So he sent Binyamin with them.''