In The Name of Allaah, The Most Merciful, The Bestower of Mercy.

Some people underestimate the Power of their Lord, speculate about the unseen, fear-mongering and say, “Such and such disease will never go away”; however, we say to them, “Either a  person is concocting something and speaking about something that does not exist or he knows the cure but hides it in order to use it for ulterior motives, or he genuinely does not know and should remain quiet”. As for the other group, they completely rely on themselves and say, “It will go away and we’ll overcome it” without saying, “InShaaAllaah!”

They Underestimate The Power of Allaah, But The Believers Do Not Underestimate The Power of Allaah

Allaah [The Exalted] said:

وَمَا قَدَرُواْ ٱللَّهَ حَقَّ قَدۡرِهِۦ وَٱلۡأَرۡضُ جَمِيعً۬ا قَبۡضَتُهُ ۥ يَوۡمَ ٱلۡقِيَـٰمَةِ وَٱلسَّمَـٰوَٲتُ مَطۡوِيَّـٰتُۢ بِيَمِينِهِۦ‌ۚ سُبۡحَـٰنَهُ ۥ وَتَعَـٰلَىٰ عَمَّا يُشۡرِكُونَ

They made not a just estimate of Allah such as is due to Him. And on the Day of Resurrection the whole of the earth will be grasped by His Hand and the heavens will be rolled up in His Right Hand. Glorified is He, and High is He above all that they associate as partners with Him! [Ref 1]

Ibn Abbaas [radiyallaahu-anhumaa] said, “A Jewish Rabbi came to Allaah’s Messenger [sallal laahu alayhi wasallam] and said, ‘O Muhammad! We learn that Allaah will put all the heavens on one finger, and the earths on one finger, and the trees on one finger, and the water and the dust on one finger, and all the other created beings on one finger. Then He will say, ‘I am the King’. Thereupon the Prophet [sallal laahu alayhi wasallam] smiled until his premolar teeth became visible, and that was the confirmation of the speech of the Rabbi. Then he recited: [وَمَا قَدَرُواْ ٱللَّهَ حَقَّ قَدۡرِهِۦ  – They made not a just estimate of Allah such as is due to Him (i.e. Allaah)].[Ref2]

Ibn Abbaas [radiyallaahu anhumaa] said, “This Aayah addresses the disbelievers, but as for those who believe that Allaah is able to do all things, then certainly they give Allaah a just estimate such as is due to Him. [Ref 3].

They Do Not Say InShaaAllaah, But The Believers Say, “InShaaAllaah, We Will Find a Cure”.

Allaah [The Exalted] said:

وَلَا تَقُولَنَّ لِشَاْىۡءٍ إِنِّى فَاعِلٌ۬ ذَٲلِكَ غَدًا

إِلَّآ أَن يَشَآءَ ٱللَّهُ‌ۚ وَٱذۡكُر رَّبَّكَ إِذَا نَسِيتَ وَقُلۡ عَسَىٰٓ أَن يَهۡدِيَنِ رَبِّى لِأَقۡرَبَ مِنۡ هَـٰذَا رَشَدً۬ا

And never say of anything, “I shall do such and such thing tomorrow.” Except (with the saying), “If Allah will!” And remember your Lord when you forget and say: “It may be that my Lord guides me unto a nearer way of truth than this.” [Ref 4]

Allaah [The Exalted] forbade a person from saying –  in relation to affairs of the future, “I will do such and such” without attaching it to the Will of Allaah, because of the danger in the affair, which is tantamount to speaking about the unseen future and none knows whether he will do something or not. [Ref 5] [وَٱذۡكُر رَّبَّكَ إِذَا نَسِيتَ وَقُلۡ عَسَىٰٓ أَن يَهۡدِيَنِ رَبِّى لِأَقۡرَبَ مِنۡ هَـٰذَا رَشَدً۬ا  – And remember your Lord when you forget and say: “It may be that my Lord guides me unto a nearer way of truth than this”]- Meaning, if you forget to say inshaaAllaah, then say inshaaAllaah even if after a day, a month or a year. [Ref 6]

They Do Not Learn a Lesson After Being Afflicted Due to Pride And Disbelief, But The Believers Learn a Lesson From The Story of The Owners of The Two Gardens

Allaah [The Exalted] said:

وَٱضۡرِبۡ لَهُم مَّثَلاً۬ رَّجُلَيۡنِ جَعَلۡنَا لِأَحَدِهِمَا جَنَّتَيۡنِ مِنۡ أَعۡنَـٰبٍ۬ وَحَفَفۡنَـٰهُمَا بِنَخۡلٍ۬ وَجَعَلۡنَا بَيۡنَہُمَا زَرۡعً۬ا

كِلۡتَا ٱلۡجَنَّتَيۡنِ ءَاتَتۡ أُكُلَهَا وَلَمۡ تَظۡلِم مِّنۡهُ شَيۡـًٔ۬ا‌ۚ وَفَجَّرۡنَا خِلَـٰلَهُمَا نَہَرً۬ا

وَكَانَ لَهُ ۥ ثَمَرٌ۬ فَقَالَ لِصَـٰحِبِهِۦ وَهُوَ يُحَاوِرُهُ ۥۤ أَنَا۟ أَكۡثَرُ مِنكَ مَالاً۬ وَأَعَزُّ نَفَرً۬ا

وَدَخَلَ جَنَّتَهُ ۥ وَهُوَ ظَالِمٌ۬ لِّنَفۡسِهِۦ قَالَ مَآ أَظُنُّ أَن تَبِيدَ هَـٰذِهِۦۤ أَبَدً۬ا

وَمَآ أَظُنُّ ٱلسَّاعَةَ قَآٮِٕمَةً۬ وَلَٮِٕن رُّدِدتُّ إِلَىٰ رَبِّى لَأَجِدَنَّ خَيۡرً۬ا مِّنۡهَا مُنقَلَبً۬ا

قَالَ لَهُ ۥ صَاحِبُهُ ۥ وَهُوَ يُحَاوِرُهُ ۥۤ أَكَفَرۡتَ بِٱلَّذِى خَلَقَكَ مِن تُرَابٍ۬ ثُمَّ مِن نُّطۡفَةٍ۬ ثُمَّ سَوَّٮٰكَ رَجُلاً۬

لَّـٰكِنَّا۟ هُوَ ٱللَّهُ رَبِّى وَلَآ أُشۡرِكُ بِرَبِّىٓ أَحَدً۬ا

وَلَوۡلَآ إِذۡ دَخَلۡتَ جَنَّتَكَ قُلۡتَ مَا شَآءَ ٱللَّهُ لَا قُوَّةَ إِلَّا بِٱللَّهِ‌ۚ إِن تَرَنِ أَنَا۟ أَقَلَّ مِنكَ مَالاً۬ وَوَلَدً۬ا

فَعَسَىٰ رَبِّىٓ أَن يُؤۡتِيَنِ خَيۡرً۬ا مِّن جَنَّتِكَ وَيُرۡسِلَ عَلَيۡہَا حُسۡبَانً۬ا مِّنَ ٱلسَّمَآءِ فَتُصۡبِحَ صَعِيدً۬ا زَلَقًا

أَوۡ يُصۡبِحَ مَآؤُهَا غَوۡرً۬ا فَلَن تَسۡتَطِيعَ لَهُ ۥ طَلَبً۬ا

وَأُحِيطَ بِثَمَرِهِۦ فَأَصۡبَحَ يُقَلِّبُ كَفَّيۡهِ عَلَىٰ مَآ أَنفَقَ فِيہَا وَهِىَ خَاوِيَةٌ عَلَىٰ عُرُوشِہَا وَيَقُولُ يَـٰلَيۡتَنِى لَمۡ أُشۡرِكۡ بِرَبِّىٓ أَحَدً۬ا

وَلَمۡ تَكُن لَّهُ ۥ فِئَةٌ۬ يَنصُرُونَهُ ۥ مِن دُونِ ٱللَّهِ وَمَا كَانَ مُنتَصِرًا

هُنَالِكَ ٱلۡوَلَـٰيَةُ لِلَّهِ ٱلۡحَقِّ‌ۚ هُوَ خَيۡرٌ۬ ثَوَابً۬ا وَخَيۡرٌ عُقۡبً۬ا

And put forward to them the example of two men; unto one of them We had given two gardens of grapes, and We had surrounded both with date-palms; and had put between them green crops (cultivated fields etc.). Each of those two gardens brought forth its produce, and failed not in the least therein, and We caused a river to gush forth in the midst of them. And he had property (or fruit) and he said to his companion, in the course of mutual talk: I am more than you in wealth and stronger in respect of men.” And he went into his garden while in a state (of pride and disbelief) unjust to himself. He said: “I think not that this will ever perish. “And I think not the Hour will ever come, and if indeed I am brought back to my Lord, (on the Day of Resurrection), I surely shall find better than this when I return to Him.” His companion said to him, during the talk with him: “Do you disbelieve in Him Who created you out of dust (i.e. your father Adam), then out of Nutfah (mixed semen drops of male and female discharge), then fashioned you into a man? “But as for my part (I believe) that He is Allah, my Lord and none shall I associate as partner with my Lord. It was better for you to say, when you entered your garden: ‘That which Allah wills (will come to pass)! There is no power but with Allah ‘. If you see me less than you in wealth, and children. “It may be that my Lord will give me something better than your garden, and will send on it Husban (torment, bolt, etc.) from the sky, then it will be a slippery earth. “Or the water thereof (of the gardens) becomes deep-sunken (underground) so that you will never be able to seek it.” So his fruits were encircled (with ruin). And he remained clapping his hands with sorrow over what he had spent upon it, while it was all destroyed on its trellises, he could only say: “Would I had ascribed no partners to my Lord!” And he had no group of men to help him against Allah, nor could he defend or save himself. There (on the Day of Resurrection), Al-Walayah (the protection, power, authority and kingdom) will be for Allah (Alone), the True God. He (Allah) is the Best for reward and the Best for the final end. (La ilaha ill-Allah none has the right to be worshipped but Allah). [Ref 7]

They Say, “Such and Such Disease Will Never Go Away”, Believers Say, “There Is Cure For Every Disease And There Is Neither Power Nor Might Except With Allaah”

Allaah [The Most High] stated that Ibraaheem [alayhis salaam] said: [وَإِذَا مَرِضۡتُ فَهُوَ يَشۡفِينِ – And when I am ill, it is He [Allaah] Who cures me]. [Surah Ash-Shu’araa. Aayah 80] – Meaning: When I become sick, none is able to heal me, except Allaah, by way of the means that may lead to recovery [i.e. by His Will]. [Ref 8]

Abdullah Ibn Mas’ood [radiyallaahu-ahu] said, “Allaah’s Messenger [sallal laahu alayhi wasallam said, ‘Allaah did not send down any disease except that he also sent its cure.” In another narration, the Messenger [sallal laahu alayhi wasallam] said, ‘One who has knowledge of it knows it, and one ignorant of it is ignorant’”. [Ref 9]

لا حول ولا قوة الا بالله

Al-Harwee [rahimahullaah] said that Abu Haytham [rahimahullaah] said, “Al-Hawl [i.e. might] is Al-Haraka [movement], meaning, there is no movement nor ability except by the Will of Allaah”. And it is said, “There is no might to repel evil nor any power to reach good except by the Will of Allaah”. [Ref 10]

They Speculate And Harbour Evil Intentions, But Believers Neither Speculate Nor Harbour Corrupt Intents, Goals and Aims

[إِن يَتَّبِعُونَ إِلَّا ٱلظَّنَّ وَمَا تَهۡوَى ٱلۡأَنفُسُ‌ۖ  – They follow but a guess and that which they themselves desire]. There is a tremendous benefit derived from this, because the one deprived of sound Eemaan and the sound creed sent down as revelation by Allaah- The Lord of the Aalameen, then his affair is one of two: Corruption in Knowledge or Corruption in his Intent– corruption in knowledge occurs as a result of following conjecture and corruption in one’s intent occurs as a result of following desires, or the person may combine both of them. [11]

Finally: Recklessness And Immorality Occurs When Militant Atheists And Crafty Wealthy Opportunists Are Given Authority In The Knowledge of Medicine And Other Worldly Affairs – [Admonitions By Imaam As-Sadi and Shaikh Rabee]

https://salaficentre.com/2020/05/29/recklessness-and-immorality-occurs-when-militant-atheists-and-crafty-wealthy-opportunists-are-given-authority-in-the-knowledge-of-medicine-and-other-worldly-affairs-admonitions-by-imaam-as/

[Ref1: Surah Az-Zumar. Aayah 67]

[Ref2: Saheeh al-Bukhaari. Number 4811]

[Ref3: Zaadul Maseer Fee Ilmit Tafseer by Imaam Ibnul Jawzi (rahimahullaah)]

[Ref 4: Surah Al-Kahf. Aayaat 23-24]

[Ref 5: Tafseer As-Sadi]

[Ref 6: Zaadul Maseer Fee Ilmit Tafseer]

[Ref 7: Surah al-Kahf. Aayaat 32-44]

Ref 8: Tafseer Ibn Katheer

Ref 9: Sunan Ibn Maajah 3438 and declared authentic by Imaam Albaanee in Sisilah As-Saheehah 4/208

Ref 10: Sharh Saheeh Muslim 4/87]

[Ref 11: An Excerpt from Sharh Kitaab At-Tawheed. Lesson 4. By Shaikh Abdur Razzaaq Al-Badr.  Slightly paraphrased]