The Virtues of Surat Al-Fatihah
Question

Why is Surat Al-Fatihah so important? What is its virtue?
Praise be to Allah.Surat Al-Fatihah is very important, and its virtues and blessings are many. They include the following:

Surat Al-Fatihah is one of the pillars or essential parts of the prayer, and no prayer is valid without it. Al-Bukhari (756) and Muslim (394) narrated from `Ubadah ibn As-Samit (may Allah be pleased with him) that the Messenger of Allah (blessings and peace of Allah be upon him) said: “There is no prayer for the one who does not recite the Opening of the Book (i.e., Surat Al-Fatihah).”

An-Nawawi (may Allah have mercy on him) said:
“This indicates that it is obligatory to recite Al-Fatihah and that it is a must and nothing else can take its place, except for one who is unable to recite it. This is the view of Malik and Ash-Shafi`i, and of the majority of scholars among the Companions and Successors of the Companions (Tabi`un), and those who came after them.” (End quote)

Surat Al-Fatihah is the best surah of the Quran. At-Tirmidhi (2875) narrated – and classed his report as authentic– from Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (blessings and peace of Allah be upon him) said to Ubayy ibn Ka`b (may Allah be pleased with him): “Would you like me to teach you a Surah the like of which was not revealed in the Torah or in the Gospel or in the Psalms or in the Furqan [Quran]?” He said: Yes, O Messenger of Allah. The Messenger of Allah (blessings and peace of Allah be upon him) said: “What do you recite in prayer?” So he recited the Essence of the Quran [i.e., Surat Al-Fatihah]. The Messenger of Allah (blessings and peace of Allah be upon him) said: “By the One in Whose hand is my soul, nothing like it was revealed in the Torah or in the Gospel or in the Psalms or in the Furqan.” (Classed as authentic by Al-bani in Sahih At-Tirmidhi)
Surat Al-Fatihah is the seven oft-repeated ones, of which Allah says (interpretation of the meaning): {And We have certainly given you, [O Muhammad], seven of the often repeated [verses] and the great Quran} [Al-Hijr 15:87]

Al-Bukhari (4474) narrated from Abu Sa`id Al-Mu`alla (may Allah be pleased with him) that the Messenger of Allah (blessings and peace of Allah be upon him) said to him: “I shall surely teach you a surah that is one of the greatest surahs in the Quran before you leave the mosque.” Then he took me by the hand and when he wanted to leave, I said to him: Did you not say: I shall surely teach you a surah that is one of the greatest surahs in the Quran? He said: “Al-hamdu Lillahi Rabbi l-‘alameen [i.e., Al-Fatihah]. It is the seven oft-repeated verses, and the great Quran that I have been given.”
Al-Hafidh (may Allah have mercy on him) said:
“There was a difference of scholarly opinion concerning the reason why it was called Mathani. It was said that it is because it is repeated (Tuthanna) in every Rak`ah; or because Allah, may He be Exalted, is praised (Yuthna) in them; or because it was given exclusively (Ustuthniyat) to this Ummah and was not sent down to those who came before it.” (End quote)
They combine seeking to draw near to Allah, may He be Exalted, by praising and glorifying Him, and seeking to draw near to Him by showing humility to Him and affirming His oneness (Tawhid). Then comes the most important request for the most sought-after thing, which is guidance, after the two means of drawing close to Allah. So the one who offers this supplication will be granted a response. (Madarij As-Salikin, 1/24)

Despite its brevity, Surat Al-Fatihah includes all three types of Tawhid: Tawhid Ar-rububiyyah (oneness of divine Lordship), Tawhid Al-Uluhiyyah (oneness of divinity) and Tawhid Al-Asma’ was-Sifat (oneness of the divine names and attributes). (Madarij As-Salikin, 1/24-27)
Surat Al-Fatihah refers to well-being for both hearts and bodies.

Ibn Al-Qayyim (may Allah have mercy on him) said:
“With regard to it referring to well-being for hearts (spiritual well-being), it is one hundred percent effective. The cause of hearts becoming sick and ailing is based on two things: corruption of knowledge and corruption of intention. From these two result two lethal sicknesses, namely misguidance and anger. Misguidance results from corruption of knowledge (or lack of sound knowledge), and anger results from corruption of intention (or lack of sound intention). These two diseases are the main causes for the undermining of all spiritual well-being. Guidance to the straight path guarantees healing from the sickness of misguidance, hence asking for this guidance is the most important supplication and the most obligatory supplication that each person must offer every day and night, in every prayer, because it is so essential and because the person’s need for the guidance that is sought is so great; nothing else can take the place of this request.
Attaining the true meaning of {It is You we worship and You we ask for help} [Al-Fatihah 1:5] in terms of knowledge, understanding, and putting it into practice so that it becomes one’s attitude and behaviour will guarantee healing from the sickness of corruption of the heart and the intention.
With regard to it guaranteeing healing of the body, we will mention regarding that what has been narrated in the Sunnah and what was supported by medical proof, and has been tried and tested.
As for what is indicated by the Sunnah, it is narrated in an authentic report from Abu Al-Mutawakkil An-Naji, from Abu Sa`id Al-Khudri, that some of the companions of the Prophet (blessings and peace of Allah be upon him) passed by a tribe of the Arabs… And he narrated the hadith that speaks of doing Ruqyah by reciting Al-Fatihah. Then he said:
This hadith refers to the healing of the man who had been stung by a scorpion, by means of reciting Al-Fatihah over him; it sufficed him so that he needed no other medicine, and perhaps it was more efficacious than any medicine could have been.
This happened despite the fact that Al-Fatihah was recited over someone who was not the best candidate for this treatment – either because this tribe was not Muslim, or because they were stingy and mean – so how about if the person had been a good candidate for that?” (Madarij As-Salikin 1/52-55)
Then he said:
“I used to suffer from severe pains, to the extent that I could hardly move, during tawaf and at other times. So I began to recite Al-Fatihah into my hands and wipe them over the site of the pain, and it was as if the pain was a small stone that dropped off. I tried that many times. And I used to take a cup of Zamzam water and recite Al-Fatihah over it several times and then drink it, and I found a great deal of benefit and strength in that, that I never got from any other medicine.” (End quote from Madarij As-Salikin, 1/58)

Surat Al-Fatihah is a refutation of all the followers of falsehood among various religions and sects, and it is a refutation of the followers of innovation and misguidance among this ummah.

This is known in two ways: general and detailed.
To explain further, the straight path refers to knowing the truth, giving it precedence over everything else, loving it, and adhering to it, calling others to it, and striving against its enemies as much as possible.
The truth is the path that was followed by the Messenger of Allah (blessings and peace of Allah be upon him) and his companions, and what he brought in terms of both knowledge and practice with regard to the attributes of the Lord, may He be glorified, and His names, His oneness, His commands and prohibitions, and His promises and warnings, and with regard to the facts connected to faith, which are the stages of those who are journeying towards Allah, may He be exalted. All of that is to be learned only from the Messenger of Allah (blessings and peace of Allah be upon him), to the exclusion of the views, situations, ideas and suggestions of other men.” (Madarij As-Salikin,  1/58)

Surat Al-Fatihah sums up all the meanings of the divinely-revealed Books.”(Madarij As-Salikin, 1/74).
Surat Al-Fatihah contains the most beneficial of supplications.

Shaykh Al-Islam Ibn Taymiyah (may Allah have mercy on him) said: “I have thought about the most beneficial of supplications, and it is asking for help to do that which pleases Allah. Then I found it in Al-Fatihah, in the verse (interpretation of the meaning): {It is You we worship and You we ask for help} [Al-Fatihah 1:5].”
To sum up, Surat Al-Fatihah is the key to all goodness and happiness in this world and the hereafter.
Ibn Al-Qayyim (may Allah have mercy on him) said:
“The Opening of the Book, the Essence of the Quran, the seven oft-recited verses, the complete healing, the beneficial remedy, the perfect Ruqyah, the key to independence of means and success, the preserver of strength, that wards off worry, distress, fear and grief, is for the one who appreciates its value and gives it its due, and tries to apply it in the proper manner to treat his sickness, and knows how to seek healing and treat sickness with it.
When one of the Companions  attained that and treated the one who had been stung by reciting it as Ruqyah over him, he recovered immediately. The Prophet (blessings and peace of Allah be upon him) said to him: “How did you know it is a Ruqyah?”
Whomever Allah guides and helps by means of deep insight to understand the subtle meanings of this surah and what it contains of: affirmation of Allah’s oneness, knowledge of His Essence, names, attributes and actions; and affirmation of Islamic teachings, predestination and the Day of Resurrection; and affirmation of the oneness of Lordship and divinity; and what it contains of complete trust and delegating one’s affairs to the One Who has control of all things, to Him be all praise, for in His hand is all goodness and all things return to Him; and what it contains of expressing the need to seek guidance, which is the basis of happiness in this world and the hereafter, and he understands how its meanings are connected to bringing benefits and warding off ills in both realms; and he knows that ultimate and perfect consequences and great blessings are connected to this surah and dependent on having a deep understanding of it and believing in it … then Al-Fatihah will help him so that he will have no need of many medicines and Ruqyahs; through which he will be able to open all doors of goodness and ward off harm and the causes thereof.” (Zad Al-Ma`ad  4/318)
And Allah knows best.