Al-Furqan 25:53

۞ وَهُوَ ٱلَّذِى مَرَجَ ٱلْبَحْرَيْنِ هَـٰذَا عَذْبٌ فُرَاتٌ وَهَـٰذَا مِلْحٌ أُجَاجٌ وَجَعَلَ بَيْنَهُمَا بَرْزَخًا وَحِجْرًا مَّحْجُورًا

Wahuwa alladhī maraja l-baḥrayni hādhā ʿadhbun furātun wahādhā mil'ḥun ujājun wajaʿala baynahumā barzakhan waḥij'ran maḥjūran

And it is He who has released [simultaneously] the two seas [i.e., bodies of water], one fresh and sweet and one salty and bitter, and He placed between them a barrier and prohibiting partition.