In the Holy Qur'an

Verily in the Heavens and the Earth are Signs for those who believe. And in your (own) creation and in what He spreads abroad of animals there are signs for a people that are sure; And (in) the variation of the night and day, and (in) what Allah sends down of sustenance from the clouds, then gives life thereby to the Earth after its death, and (in) the changing of the winds, there are signs for a people who understand (45:3-5)

In the Traditions

Imam Ali said, "Wonder at man, who observes with a ball of fat (the eye), who talks with a lump of flesh (the tongue), who listens by means of a bone (the inner ear) and breathes through a hole in the flesh (the nose)."

Imam Jafar said, "Consider the universe together with its sun, moon, stars and Zodiac, which revolve perpetually in accordance with a definite decree and judgement to bring about numerous benefits to the denizens of the earth, variegated animal and vegetable kingdoms through the changes in the four seasons, the days and nights, which have been expatiated to you. Can any man with a discerning mind think that such a regulated plan and design on which depend the order and organisation of the universe, can come about without the Omniscient Designer?

If someone says that mere chance has brough this about, why does he no say that same thin in connection with the Persian-wheel which he sees revolving, irrigating a garden planted with trees and vegetation?

He sees all its compnents parts manugactured according to a definite plan, each part coupled with the other on a patern to serve the needs of the garden and its contents."