Prophet Muhammad (SAW) said "I am leaving among you something which is very important and should be followed, you will not go astray if you get hold of it after I am gone, one part of it being more important than the other: Allah's Book, which is a rope stretched from Heaven to Earth, and my close relatives, who belong to my household. These two will not separate from one another till they come down to the reservoir, so consider how you act regarding them after my departure." (Tirmidhi, Sahih Muslim)