﴿ كِلْتَا ٱلْجَنَّتَيْنِ ءَاتَتْ أُكُلَهَا وَلَمْ تَظْلِم مِّنْهُ شَيْـًۭٔا ۚ وَفَجَّرْنَا خِلَٰلَهُمَا نَهَرًۭا ﴾

“Each of the two gardens yielded its produce and never failed therein in any way, for We had caused a stream to gush forth in the midst of each of them.”

Each of the two gardens kiltā ‘each of the two’ is a singular noun that indicates a dual number; and the entire clause is the subject yielded ātat is the predicate thereof its produce its fruit without stinting diminishing anything thereof. And We caused a stream to gush forth therein to run through them.