Sheikh `Abd Allah b. Sardâr , lecturer at the `Umawî Mosque in Madinah
The issue of reciting Sûrah al-Fâtihah by the congregation following the imam is a matter of disagreement among scholars.
In brief, I would say:
Some scholars do not allow the recitation of Sûrah al-Fâtihah behind the imam. They support their opinion with the hadîth “When the imam reads, then be silent.” [Sahîh Muslim (404)] It is indeed an authentic hadîth.
However, reciting Sûrah al-Fâtihah is also important because of another hadîth. The Prophet (peace be upon him) “There is no prayer for the one who does not read al-Fatihah.” [Sahîh al-Bukhârî (756) and Sahîh Muslim (394)]
Those who advocate not reading behind the imam answer this by citing the hadîth: “Whoever is praying behind the imam, then the imam’s reading is a reading for him as well.” [Sunan Ibn Mâjah (850) and Musnad Ahmad (14643)] However, this is a weak hadîth.
The preferred opinion is that the person who prays behind the imam should listen to the imam while he is reading Sûrah al-Fâtihah and read it to himself thereafter. When he does so, however, he must take care that his reading is so quiet that he does not cause any disturbance.
Someone asked Abû Hurayrah about reading Sûrah al-Fâtihah behind the imam. He replied: “Read it to yourself.” [Sahîh Muslim (395)]
This has been a matter of disagreement for a long time. If we prefer one opinion, this does not mean we degrade others who differ.
Muslims should not exaggerate the importance of this issue. One way of exaggerating the importance of this matter is by claiming that someone else’s prayers are invalid or by accusing someone of beings an innovator. This is all wrong.
For another opinion, please refer to the fatwâ on our archive by Sheikh Salman al-Oadah entitled "Reciting Sûrah al-Fâtihah behind the imam"
Source: Islam Today