John Chrysostom
After stating this, he entrusted them into custody. This action serves to examine their emotions and reveals his affection for his brother through his treatment of them.
So he put them in prison three days.
וַיֶּאֱסֹ֥ף אֹתָ֛ם אֶל־מִשְׁמָ֖ר שְׁלֹ֥שֶׁת יָמִֽים׃
3 Church Fathers comment on this verse
After stating this, he entrusted them into custody. This action serves to examine their emotions and reveals his affection for his brother through his treatment of them.
He imprisoned them for three days so they could experience the suffering that Joseph endured for many years in captivity.
To allow for the selection of someone to return to the Father and bring back the last sibling may have been the purpose, as initially, no one stepped forward to take on this sorrowful mission.
Passages read together with this verse.