[35].Surah Fatir [The Originator of Creation]: Ayat 12

১২. দু’টি সমুদ্র সমান হয় না- একটি মিঠা ও তৃষ্ণানিবারক এবং অপরটি লোনা। ঊভয়টি থেকেই তোমরা তাজা গোশত (মৎস) আহার কর এবং পরিধানে ব্যবহার্য গয়নাগাটি আহরণ কর। তুমি তাতে তার বুক চিরে জাহাজ চলতে দেখ, যাতে তোমরা তার অনুগ্রহ অন্বেষণ কর এবং যাতে তোমরা কৃতজ্ঞতা প্রকাশ কর।

Ayat 12. And the two seas (kinds of water) are not alike, this fresh sweet, and pleasant to drink, and that saltish and bitter. And from them both you eat fresh tender meat (fish), and derive the ornaments that you wear. And you see the ships cleaving (the sea­water as they sail through it), that you may seek of His Bounty, and that you may give thanks.

Tafseer of Surah Fatir Ayat 12. Nor are the two bodies of flowing water alike, the one palatable, sweet, and pleasant to drink, and the other, salt and bitter. Yet from each (kind of water) do ye eat flesh fresh and tender, and ye extract ornaments to wear; and thou seest the ships therein that plough the waves, that ye may seek (thus) of the Bounty of Allah that ye may be grateful. See 25:53. The great salt Ocean with its seas and gulfs is all one; and the great masses of sweet water in rivers, lakes, ponds, and underground springs are also one; and each is connected with the other by the constant circulation going on, which sucks up vapors, carries them about in clouds or atmospheric moisture, and again brings them condensed into water or snow or hail to mingle with rivers and streams and get back into the Ocean. For this whole passage see 16:14. Both from the sea and from rivers and lakes we get fish, of which some kinds have a flesh particularly fresh and tender, and of a most delicate flavor. Such as pearls and coral from the sea, and such delicately tinted stones as the 'Aqiq (car-nelian), the agate, the goldstone, or other varieties of quartz pebbles found in riverbeds, and considered as gems. Many such are found in the Ken river in Banda District (in India). Some river sands also yield minute quantities of gold. In large navigable rivers and big lakes like those of North America, as well as in the sea, there are highways for shipping and commerce. (R).

Hazrat Abu Musa (May Allah be pleased with him) reported: The Messenger of Allah [SAWW](PBUH) said, "The similitude of guidance and knowledge with which Allah has sent me is like a rain which has fallen on some ground. A fertile part of earth has absorbed water and brought forth much grass and herbs. Another part, which is solid, held the water and Allah benefits men thereby, who drank and gave others to drink, and used it for irrigation. But some of it has fallen on a portion of sandy land which neither retains the water nor produces herbage. Such is the likeness of the man who understands the religion of Allah and who gets benefit of what Allah has sent me with; he learns and teaches others. It is also the likeness of the man who neither raises his head on that account (meaning he does not benefit from what the Prophet  [SAWW](PBUH) was sent with) nor accepts Allah's Guidance with which I am sent". [Al-Bukhari Book 01, Chapter 03, Hadith # 079] 

Lesson: as mentioned above in Surah Fatir Ayat 12. that you may seek of His Bounty, and that you may give thanks” In this Hadith the guidance and knowledge which was sent to mankind through the Prophet (PBUH) is compared to the rain which is beneficial, because this knowledge resuscitates the dead hearts as does the rain to a barren land. One who makes use of this knowledge is likened to a good soil, and one who acquires this knowledge and imparts it to others but does not put it into practice is considered akin to a hard land which holds water and other people utilize it. A person who neither learns it nor acts upon it is like a desolate land which neither holds water nor produces anything. Such a person is the worst of all because he neither himself benefits from it nor lets others make use of it. This Hadith induces one to acquire knowledge, impart it to others, put it into actual practice and warns people from neglecting this duty.