The Prophet (peace be upon him) raised his head toward the heavens and said:
"The stars are the protection for the sky - when the stars have gone, that which has been forewarned will come to the sky. I am the protection for my Companions (radhiAllaahu 'anhu) - when I have gone, that which has been forewarned will come to my Companions. My Companions are the protection for this Ummah - when they have gone, that which has been forewarned will come to this Ummah."
--Saheeh Muslim