Shaikh Al-Fawzan (may Allah preserve him) stated:
The Majority of the scholars hold the position that the recital of Surah Al-Fātihah is obligatory, and that the one who does not recite it, then his prayer is invalid, due to the saying of the Prophet (ﷺ): “There is no prayer for the one who does not recite the opening Sūrah of the Book.” (Bukhāree 756; Muslim 394). This refers to the one who is able to recite it. As for the one who is unable to recite it or unable to memorise it, then it is upon him to recite what is easy for him from the verses of the Qur’an other than Al-Fātihah. If he does not have anything of the Qur’an memorised, then he merely performs Dhikr (remembrances of Allah) such as: subhānallāh, wal-hamdulillāh, wa lā ilāha illallāh, wallāhu akbar, wa lā hawla wa lā quwwata illā billāh. This is due to the saying of the Messenger (ﷺ): “When you stand for the prayer say, allāhu akbar. If you have something of the Qur’an memorised, recite it, otherwise you should praise Allah (al-hamdulillāh), declare His greatness (Allāhu akbar) and His sole right of worship (lā ilāha illallāh), then you should bow…” (Abu Dawood 861, Tirmidhee 302)
The majority of the scholars hold that the recital of Suratul-Fātihah is obligatory upon the imām leading the prayer and when one prayers on his own. As for the one who is praying behind the imām, then the scholars have differed regarding that into three viewpoints:
The first saying: The recital of Al-Fātihah is obligatory upon everyone who prays including the imām and the one one following him in prayer. This is due to the saying of the Messenger (ﷺ):“There is no prayer for the one who does not recite the Opening Sūrah of the Book.” So this is general for everyone performing the Salāh. And the saying of the Messenger (ﷺ): “Perhaps you recite behind your imām?” They responded: “Yes, O Messenger of Allāh.” So he said: “Do not do that, except for the Opening Sūrah of the Book, for indeed there is no prayer for the one who does not recite it.” (From ‘Ubādah Ibn Sāmit, reported by Abu Dawood 824; An-Nasā’ee 919) This is the position of Imām Ash-Shāfi’ee, and a group of the scholars of hadeeth such as Imām al-Bukhāree and others. They held its recital to be obligatory upon the imām leading the prayer, the one who prays behind him, and the one who prays alone.
The second saying: The recital is not obligatory behind the imām. That is because the recitation of the imām suffices the one following him due to the saying of the Prophet (ﷺ):“Whoever has an imām [leading him in prayer] then the recitation of the imām is his recitation [also].” (Narrated from Jābir and reported by Ahmad 14698; Ibn Mājah 850; Al-Bayhaqee in his Sunan 2898 – and Al-Albānee declared it to be hasan (good) in his checking of Ibn Mājah; see Al-Irwā’, 850) However, there is some speech concerning the chain of narration of this hadeeth. These scholars also use as a proof the saying of Allah, the Most High,
وَإِذَا قُرِئَ الْقُرْآنُ فَاسْتَمِعُوا لَهُ وَأَنصِتُوا لَعَلَّكُمْ تُرْحَمُونَ
“When the Quran is recited, listen to it and be silent that you may receive mercy.” (Al-A’rāf 7:204) The point of evidence here is that Allāh, the Mighty and Majestic, commanded with listening to the the recitation of the Qur’an and to remain silent. And this verse was revealed concerning listening during the Prayer (Salāh), meaning: When the imām is reciting then upon the one who is following him is to remain silent and listen because the imām is reciting for himself and for those following behind him. This is the view of Abu Hanīfah and Ahmad Ibn Hanbal.
The third saying: This is the view of Imām Mālik, and the prefered opinion of Shaykhul-Islām Ibn Taymiyyah and a group of scholars: that it is obligatory upon the one following the imām to recite Al-Fātihah [to himself] in the silent prayers wherein the imām is not reciting aloud, such as Dhuhr and ‘Asr. And as for the loud prayers, then the recitation of the imām suffices him, and in these loud prayers it is upon the one following the imām to remain silent and listen. These scholars say that with this, a person gathers [and acts] upon all the proofs. So the evidences that obligate the recital of Al-Fātihah are to be practiced in the silent prayers. The other proofs along with the noble verse are to be practiced in the loud prayers. This saying is the most balanced, inshā’-Allāh.
See Duroos minal-Qur’ānil-Kareem pp. 37-39.