(a) Sayyiduna Abu al-Darda' (may Allah be pleased with him) says: Whether the imam recites aloud or silently, do not leave off Surah al-Fatihah behind the imam. These are the words of Kathir.
(b) Ali and Ibn Abi al-Hawari added: "Even if you recite it while you are bowing."
(c) Amr alone added this: If the imam is bowing, then recite Surah al-Fatihah when you are sure that you will reach its end (that is, recite it completely).
(d) Among them is Jabir bin Abdullah al-Ansari (may Allah be pleased with them both).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2943