[The brothers] said, "Its recompense is that he in whose bag it (12:75)

﴿قَالُوا جَزَاؤُهُ مَن وُجِدَ فِي رَحْلِهِ فَهُوَ جَزَاؤُهُ ۚ كَذَٰلِكَ نَجْزِي الظَّالِمِينَ﴾
[ يوسف: 75]

12:75 [The brothers] said, "Its recompense is that he in whose bag it is found - he [himself] will be its recompense. Thus do we recompense the wrongdoers."

Joseph’s brothers said that the payment for any thief among them was that the person in whose bag the stolen item was found would become the slave of whoever he stole from.
This punishment of being made into a slave is the way they punished thieves.

They [Yusuf's (Joseph) brothers] said: "The penalty should be that he, in whose bag it is found, should be held for the punishment (of the crime). Thus we punish the Zalimun (wrong-doers, etc.)!"

phonetic Transliteration

Qaloo jazaohu man wujida fee rahlihi fahuwa jazaohu kathalika najzee alththalimeena

Abdullah Yusuf Ali - Translation

They said: "The penalty should be that he in whose saddle-bag it is found, should be held (as bondman) to atone for the (crime). Thus it is we punish the wrong-doers!"

Safi-ur-Rahman al-Mubarakpuri

They [Yusuf's brothers] said: "His penalty should be that he, in whose bag it is found, should be held for the punishment (of the crime). Thus we punish the wrongdoers!"

Page 244 English transliteration