Qur'an, Ibrahim, Surah 14:24-25
Seest thou not how Allah sets forth a parable? A goodly word like a goodly tree, whose root is firmly fixed, and its branches (reach) to the heavens of its Lord. So Allah sets forth parables for men, in order that they may receive admonition. It brings forth its fruit at all times, by the leave of its Lord. So Allah sets forth parables for men, in order that they may receive admonition.