Anyone tasted some pleasure that comes from sound understanding of the religion will engage with this parable
In The Name of Allah, The Most Merciful, The Bestower of Mercy.
Allah, The Most High, said:
أَنزَلَ مِنَ ٱلسَّمَآءِ مَآءً فَسَالَتْ أَوْدِيَةٌۢ بِقَدَرِهَا فَٱحْتَمَلَ ٱلسَّيْلُ زَبَدًا رَّابِيًا وَمِمَّا يُوقِدُونَ عَلَيْهِ فِى ٱلنَّارِ ٱبْتِغَآءَ حِلْيَةٍ أَوْ مَتَٰعٍ زَبَدٌ مِّثْلُهُۥ كَذَٰلِكَ يَضْرِبُ ٱللَّهُ ٱلْحَقَّ وَٱلْبَٰطِلَ فَأَمَّا ٱلزَّبَدُ فَيَذْهَبُ جُفَآءً وَأَمَّا مَا يَنفَعُ ٱلنَّاسَ فَيَمْكُثُ فِى ٱلْأَرْضِ كَذَٰلِكَ يَضْرِبُ ٱللَّهُ ٱلْأَمْثَالَ
He (Allah) sends down water (rain) from the sky, and the valleys flow according to their measure, but the deluge bears away the foam that mounts up to the surface, and (also) from that (ore) which they heat in the fire to make ornaments or utensils, rises a foam like unto it, thus does Allah (by parables) show forth truth and falsehood. Then, as for the foam it passes away as scum upon the banks, while that which is for the good of mankind remains in the earth. Thus Allah sets forth parables. [Ar-Ra’d 17]
Imam Ibn Al-Qayyim, may Allah have mercy upon him, said:
In Surah Ar-Ra’d, Allah gives a similitude of water and fire regarding the believers. The similitude of water symbolises the divine revelation that Allah sends down (that gives a good) life to the hearts, much like water sent down from the sky. The hearts that carry this revelation are likened to the valleys that carry the flowing water. A heart (blessed with profound strength to discern and perceive) can hold a great deal of knowledge like a large valley can hold a lot of water, while a heart (with a small room for discernment, perception, etc) can only hold a little knowledge. Hearts carry knowledge based on their ability just like deluges flow according to their capacity.
Since the valleys and the flow of deluges contain debris and other things, it carries and floats it on the surface of the water as a high foam that accumulates. However, beneath it is fresh water, which gives life to the land. The valley throws away that debris to its sides until nothing remains of it, and then Allah causes the land to be irrigated by the water that is beneath the debris, thus bringing life to the land, its people (for different uses), the trees, and the animals. Similarly, the knowledge and Iman that Allah has revealed to the hearts is carried by the hearts. However, they are influenced due to being mixed with the debris of (vain) desires and the foam of false doubts, then they are removed to the top, while knowledge, Iman, and guidance settle in the core of the heart. That impurity and foam continue to disappear gradually until they completely vanish. The beneficial knowledge and truthful Iman remain in the core of the heart, attracting people to deeply embrace, convey, and guard it.
In the authentic narration of Abu Musa, may Allah be pleased with him, the Prophet, peace and blessings of Allah be upon him, said: “The example of guidance and knowledge with which Allah has sent me is like abundant rain falling on the earth, some of which was fertile soil that absorbed the water and brought forth vegetation and grass in abundance. [And] another portion of it was hard and held the water and Allah benefited the people with it and they utilised it for drinking, making their animals drink from it, and for irrigation of the land for cultivation. [And] a portion of it was barren which could neither hold the water nor bring forth vegetation [so that land gave no benefits]. The first is the example of the person who comprehends the religion ordained by Allah and benefits (from the knowledge) that Allah has revealed through me, learns, and then teaches others. The last example is that of a person who does not care for it and does not take Allah’s guidance revealed through me. (He is like that barren land)”. [Sahih Al-Bukhari 79 and Sahih Muslim 2282]
The Prophet divided people into three categories in terms of guidance and knowledge: the first category is the inheritors of the messengers and the successors of the prophets, peace be upon them, who uphold the religion with knowledge, action, and calling to the path of Allah and His Messenger. They are truly the followers of the messengers, like a good piece of land that is fertile and produces abundant crops. They are the ones (blessed) with a combination of insight into the religion and strength in calling to it, thus they are the heirs of the prophets mentioned by Allah:
وَٱذْكُرْ عِبَٰدَنَآ إِبْرَٰهِيمَ وَإِسْحَٰقَ وَيَعْقُوبَ أُو۟لِى ٱلْأَيْدِى وَٱلْأَبْصَٰرِ
And remember Our slaves, Ibrahim (Abraham), Ishaque (Isaac), and Ya’qub (Jacob), (all) owners of strength (in worshipping Us) and (also) of religious understanding.
This group has the power of memorisation and understanding in the religion and sound interpretation, so they extract rivers of knowledge from the texts and derive treasures from them, and are blessed with a special understanding, as the leader of the believers Ali ibn Abi Talib, may Allah be pleased with him, said when asked: “Did Allah’s Messenger, peace and blessings of Allah be upon him, give you something special that he did not give to others?” He replied: “No, by the One who split the seed and created the soul, except for understanding that Allah gives to His servant in His book.” This understanding is like abundant grass and herbs that the earth has grown, and it is what distinguishes this group.
The second category of people protect the texts. Their concern is to memorise and preserve it precisely. Then people receive and learn it from them. They derive sound understanding from it, extract treasures from it, and extend it to land like fertile land that is suitable for cultivation and growth. These are the people whom the Prophet, peace and blessings of Allah be upon him, spoke about, saying, “May Allah brighten the face of a person who hears a saying of mine, understands and conveys as he hears it. Perhaps one who carries understanding does not possess (precise) understanding, and perhaps a carrier of understanding may convey it to one who has a better understanding than him”.
As for the third group: they are the most miserable of people who neither accept Allah’s guidance nor care about it. Neither memorise nor possess understanding etc.[1]
Imam as-Sadi, may Allah have mercy upon him, said:
Allah likened the guidance He revealed to His Messenger (that gives) the hearts and souls (a good life of Iman, purity, upright discernment between right and wrong, etc) to the water that brings life to plants. He likened the indispensable benefits found in the guidance to the essential benefits of rain. He likened hearts that carry the guidance and the difference between them to the valleys through which floods flow. Just as a large valley can contain a significant amount of water, a heart (endowed with deep perception and discernment) can hold vast knowledge. (Conversely), a small valley can only accommodate a small amount of water, just as a heart (with limited ability to perceive and discern) can only possess a limited amount of knowledge. And so forth.
The (vain) desires and doubts in people’s hearts, when confronted with the truth, are likened to the froth that hovers on water, concealing the valuable ore that requires purification and refinement. It lingers atop the surface, obscuring clarity, until it vanishes and dissipates, revealing solely the untainted water and authentic ore that bring advantages to humanity. Similarly, doubts and (vain) desires are continuously rejected by the heart, which combats them with solid proof and strong determination until they vanish, leaving the heart pure and clear, containing only what benefits people such as knowledge of the truth and giving it precedence, and desiring it. Falsehood goes away and is destroyed by the truth. “Indeed, falsehood is bound to vanish”. And it is said here in this Ayah: “Thus does Allah set forth parables” to clarify the truth from falsehood, guidance from misguidance. [كَذَٰلِكَ يَضْرِبُ ٱللَّهُ ٱلْأَمْثَالَ – Thus Allah sets forth parables] to make very clear the distinction between truth and falsehood, and between guidance and misguidance]. [2]
[1] An Excerpt from “Bada’i at-Tafsir al-Jami Limaa Fassarahu al-Imam Ibn Al-Qayyim” 2/80-83
[2] An Excerpt from Tafsir as-Sadi