Musnad Ahmad

A man says that I was sitting in a gathering in Madinah in which Hazrat Umar Farooq was also present. He said to one of the people, "How did you hear the Prophet (peace be upon him) describe the condition of Islam?" He replied, "I heard the Prophet (peace be upon him) say that the beginning of Islam was like a six-month-old goat, which has two teeth, then it had four teeth, then six teeth, then it had canine teeth." Upon this, Hazrat Umar said, "After the canine teeth, the return towards decline begins."