Word by Word Analysis

فَلَمَّا رَجَعُوٓا۟ إِلَىٰٓ أَبِيهِمْ قَالُوا۟ يَـٰٓأَبَانَا مُنِعَ مِنَّا ٱلْكَيْلُ فَأَرْسِلْ مَعَنَآ أَخَانَا نَكْتَلْ وَإِنَّا لَهُۥ لَحَـٰفِظُونَ 63

So when they returned to their father, they said, "O our father, [further] measure has been denied to us, so send with us our brother [that] we will be given measure. And indeed, we will be his guardians."