Sahih Bukhari
Virtues of the Quran
Volume: 006 / Book Number: 061 / Hadith Number: 571
Narrated Sufyan:
Ibn Shubruma said, "I wanted to see how much of the Qur'an can be enough (to recite in prayer) and I could not find a Surah containing less than three Verses, therefore I said to myself), "One ought not to recite less than three (Quranic) Verses (in prayer)."
Narrated Abu Mas'ud: The Prophet said, "If somebody recites the last two Verses of Surat al-Baqara at night, it will be sufficient for him.