Surah 54. Al-Qamar, Ayah 50

I.e., there is no time lag and no conceptual difference between God's "willing" the creation of a thing and His "creating" it, for "when He wills a thing to be, He but says unto it, 'Be'- and it is" ( 2:117 , 3:47 , 16:40 , 19:35 , 36:82 and 40:68 ). The comparison with the "twinkling of an eye" is, of course, merely idiomatic, i.e., based on the human concept of something instantaneous. In the present context this is - as the sequence shows - an allusion to the rapidity with which God can, if He so wills, destroy a sinful community.

 To bring anything into being.

 “Be!” And it is!

While in the life of created things there is "proportion and measure", and a lag of time or distance or circumstance, in Allah's Command, the Design, the Word, the Execution, and the Consequences are but a single Act. The simile given is that of the twinkling of an eye, which is the shortest time that a simple man can think of: the cause which occasions the twinkling, the movement of the muscles connected with it, the closing of the eyelids, and their reopening, are all almost like a simultaneous act. By way of contrast take an illustration like that of a man writing a book. He must form the design in his mind; he must prepare himself by research, collection of knowledge, or of personal experience; he must use or acquire the art of writing; he must collect the materials for writing, viz., paper, ink, pen, etc., and this will connect with a chain of manufacturing processes in which he is dependent upon other people's work and experience; then his book may have to be printed or lightographed or bound, and sold, or taken to a library, or presented to a friend, which will bring into play numerous other chains of processes, and dependence upon other people's work or skill; and the lag of Time, Space, and Circumstance will occur at numerous stages. In Allah's Command, the word "Be" (kun) includes everything, without the intervention, of or dependence upon any other being or thing whatever. And this is also another phase of the philosophy of Unity.