In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
Allaah [The Most High] said in Soorah Luqmaan Ayah 18:
وَلَا تُصَعِّرْ خَدَّكَ لِلنَّاسِ وَلَا تَمْشِ فِي الْأَرْضِ مَرَحًا إِنَّ اللَّهَ لَا يُحِبُّ كُلَّ مُخْتَالٍ فَخُورٍ
[وَلَا تُصَعِّرْ خَدَّكَ لِلنَّاسِ –And turn not your face away from men with pride] – Meaning: Do not turn away and frowning at the people with your face, being arrogant towards them and exalting (yourself). [ وَلَا تَمْشِ فِي الْأَرْضِ مَرَحًا ۖ –Nor walk in insolence through the earth] -Meaning: Out of vanity, boasting about blessings, forgetful of the one who bestowed it upon you (i.e. Allaah) and being amazed with yourself. [إِنَّ اللَّهَ لَا يُحِبُّ كُلَّ مُخْتَالٍ فَخُورٍ- Verily, Allah likes not each arrogant boaster]- Meaning: Boastful about himself, his personality and significance, and in his speech.
[Source: An Excerpt from ‘Tayseer Al-Kareem Ar-Rahmaan Fee Tafseer Kalaam Al-Mannaan’. Slightly paraphrased]