Al-Haafz Ibn Katheer said in his commentary on this verse (Tafseer 1/175): “Here Allaah explains the completeness of His power and the greatness of His authority, and that if He wills and decrees something, He simply says to it, ‘Be!’ – just once – and it is, i.e., it comes into existence as He willed it. This is like the verse in which Allaah says (interpretation of the meaning): ‘Verily, His Command, when He intends a thing, is only that He says to it, “Be!” — and it is!’ [Ya-Seen 36:82].”