Concise Quran Commentary
And Allah has created everything that walks on the face of the earth from a drop of sperm. Some walk crawling on their bellies, i.e. snakes, while some walk on two feet, i.e. humans and birds, while others walk on four legs, i.e. livestock. Allah creates whatever He wishes, including things mentioned and unmentioned. Indeed, He is capable of everything; Nothing is outside His ability.