Allah forbids His servants to strut and walk in a boastful manner:

﴿وَلاَ تَمْشِ فِى الاٌّرْضِ مَرَحًا﴾

(And walk not on the earth with conceit and arrogance.) meaning, walking in boastful manner and acting proud, like those who are arrogant oppressors.

﴿إِنَّكَ لَن تَخْرِقَ الاٌّرْضَ﴾

(Verily, you can neither rend nor penetrate the earth) means, you cannot penetrate the earth with your walking. This was the opinion of Ibn Jarir.

﴿ذَلِكَ مِمَّآ أَوْحَى إِلَيْكَ رَبُّكَ مِنَ الْحِكْمَةِ وَلاَ تَجْعَلْ مَعَ اللَّهِ إِلَـهًا ءَاخَرَ فَتُلْقَى فِى جَهَنَّمَ مَلُومًا مَّدْحُورًا ﴾

(39. This is (part) of Al-Hikmah (wisdom) which your Lord has revealed to you. And set not up with Allah any other god lest you should be thrown into Hell, blameworthy and rejected (from Allah's mercy).)