Salam, could you translate the verse 19-20 from Surah Ar Rehman and respond what does mean by "marajal bahrain"? Does that mean a specific sea?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Allah Says (what means): {He has let loose the two seas (the salt and fresh water) meeting together. Between them is a barrier which none of them can transgress.} [Quran 55:19-20]

What is meant by the two seas is the freshwater sea and the saltwater sea on this earth. The meaning of the {He has let loose the two seas (the salt and fresh water) meeting together}; is that Allah set free the freshwater and the saltwater, and made them meet. However, although they meet, yet Allah has made a barrier between them that prevents each one from mixing into the other.

This is like the Saying of Allah (which means): {And it is He Who has let free the two seas (kinds of water): this is palatable and sweet, and that is salt and bitter; and He has set a barrier and a complete partition between them.} [Quran 25:53]

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Allah knows best.