Sahih Bukhari
Virtues and Merits of the Prophet (pbuh) and his Companions
Volume: 004 / Book Number: 056 / Hadith Number: 833
Narrated Anas:
Once two men from the companions of Allah's Apostle went out of the house of the Prophet on a very dark night. They were accompanied by two things that resembled two lamps lighting the way in front of them, and when they parted, each of them was accompanied by one of those two things (lamps) till they reached their homes.