فَلَمَّا بَلَغَا مَجْمَعَ بَيْنِهِمَا نَسِيَا حُوتَهُمَا فَٱتَّخَذَ سَبِيلَهُۥ فِى ٱلْبَحْرِ سَرَبًا
Falammaa balaghaa majma'a bainihimaa nasiyaa hootahumaa fattakhaza sabeelahoo fil bahri sarabaa
but when they reached the place where the two seas meet, they had forgotten all about their fish, which made its way into the sea and swam away.
But when they reached the place where the two seas meet, they forgot their fish, and it made its way into the sea, slipping off.