Creation was made with Justice and Wisdom

Allah tells us that He created the heavens and the earth in truth, i.e. with justice.

لِيَجْزِىَ الَّذِينَ أَسَاءُواْ بِمَا عَمِلُواْ وَيِجْزِى الَّذِينَ أَحْسَنُواْ بِالْحُسْنَى

لَوْ أَرَ‌دْنَا أَن نَّتَّخِذَ لَهْوًا لَّاتَّخَذْنَاهُ مِن لَّدُنَّا إِن كُنَّا فَاعِلِينَ (Had We intended to have a pastime, We would have had it from Our own, if We were to do so. - 21:17) It means that if We were to create something for amusement, there was no need to create the earth and the sky, and We could have done so from the things around Us.

In Arabic language the word لَو is used for imaginary and non-existent things. Here also it is used in the same sense i.e. those foolish people who regard all the wonderful things of the earth and the sky objects of fun and frolic do not realize that creation on such a gigantic scale cannot be undertaken for amusement. The suggestion here is that even a person of ordinary common sense would not indulge in a project which has no serious purpose, to say nothing of Allah Ta` ala who is Supreme and Exalted.