What is the Islamic ruling if someone forgets to recite Surah Al-Fatihah during their obligatory prayer (Salah)? Does the prayer become invalid, and what should be done to rectify it?
In the name of Allah, the Most Gracious, the Most Merciful.
Reciting Surah Al-Fatihah is a fundamental pillar (Rukn) of the prayer. According to the majority of Islamic scholars, a unit of prayer (Rak’ah) is not valid without its recitation.
If a person is praying individually or leading the prayer as an Imam and completely forgets to recite Surah Al-Fatihah, that specific Rak’ah becomes invalid. They must stand up and perform another Rak’ah to replace the invalid one, and then perform the prostration of forgetfulness (Sujud al-Sahw) at the end of the prayer.
Reference:
This ruling is strictly derived from the authentic statement of the Prophet Muhammad (ﷺ):
عُبَادَةُ بْنُ الصَّامِتِ رضي الله عنه أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: “لَا صَلَاةَ لِمَنْ لَمْ يَقْرَأْ بِفَاتِحَةِ الْكِتَابِ”
Ubadah bin As-Samit (May Allah be pleased with him) reported: The Messenger of Allah (ﷺ) said: “There is no prayer for the one who does not recite the Opening of the Book (Surah Al-Fatihah).”
— [Sahih al-Bukhari: 756, Sahih Muslim: 394]
And Allah knows best.