(a) It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both): Do not leave off reciting Surah al-Fatihah in every rak'ah behind the imam, whether the imam recites aloud or silently.
(b) Among them are Sayyiduna Abdullah bin Umar bin al-Khattab and Abdullah bin Amr bin al-As (may Allah be pleased with them); the narration of Abu al-Azhar al-Duba'i from Abu al-Aliyah from Sayyiduna Ibn Umar (may Allah be pleased with them both) has already passed.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2940