"And [He] made a barrier between the two seas." The interpretation of al-Kalbi: meaning the sea of Persia and [the sea of] Rome, and the barrier is the creation [that is] between them so that neither of them transgresses against the other. "Rather, most of them do not know," meaning: their multitude.
﴿وَجعل بَين الْبَحْرين حاجزا﴾ تَفْسِيرُ الْكَلْبِيِّ: يَعْنِي: بَحْرَ فَارِسَ وَالرُّومِ، وَالْحَاجِزُ: الْخَلْقُ الَّذِي بَيْنَهُمَا فَلَا يَبْغِي أَحَدُهُمَا عَلَى صَاحِبِهِ ﴿بل أَكْثَرهم لَا يعلمُونَ﴾ يَعْنِي: جَمَاعَتهمْ.