Yazid (may Allah have mercy on him) said: I heard Sayyiduna Jabir bin Abdullah (may Allah be pleased with them both) say that in the first two rak'ahs Surah al-Fatihah is to be recited along with another surah, and in the last two rak'ahs only Surah al-Fatihah is to be recited. "There is no prayer without Surah al-Fatihah," though one may recite more.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2476