Sayyiduna Abu Hurayrah (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) said: "I am leaving among you that which, as long as you hold fast to it, or he said: act upon it, you will never go astray: 1. the Book of Allah, 2. my Sunnah."
"And they will never separate until they come to me at the Pond."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب آداب القاضي / 20337