Musnad Ahmad 175:6

'Abd al-Rahman narrated to us, from Sufyan, from Sa'd, from 'Abdullah or 'Abd al-Rahman ibn Ka'b ibn Malik—'Abd al-Rahman said: "It is a doubt," meaning Sufyan—from his father, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The likeness of the believer is like the tender stalk of a plant; the winds straighten it one time and knock it down another, until its appointed time comes to it. And the likeness of the disbeliever is like the cedar tree, standing firm upon its root; nothing affects it until its uprooting—or its being torn out—happens all at once."