Musnad Ahmad 28:562

Mu'ammal narrated to us, Hammad narrated to us, 'Ali ibn Zayd narrated to us, from Khalid ibn al-Huwayrith, from 'Abdullah ibn 'Amr, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The signs are like beads strung on a thread; if the thread is cut, they follow one another."