Iyad ibn Himar reported: The Messenger of Allah, peace and blessings be upon him, said, “Verily, Allah has revealed to me that you must be humble towards one another, so that no one oppresses another or boasts to another.”

Source: Sahih Muslim 2865

Grade: Sahih (authentic) according to Muslim

عَنْ عِيَاضِ بْنِ حِمَارٍ أَنَّهُ قَالَ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِنَّ اللَّهَ أَوْحَى إِلَيَّ أَنْ تَوَاضَعُوا حَتَّى لَا يَبْغِيَ أَحَدٌ عَلَى أَحَدٍ وَلَا يَفْخَرَ أَحَدٌ عَلَى أَحَدٍ

2865 صحيح مسلم كِتَاب الْجَنَّةِ وَصِفَةِ نَعِيمِهَا وَأَهْلِهَا بَاب الصِّفَاتِ الَّتِي يُعْرَفُ بِهَا فِي الدُّنْيَا أَهْلُ الْجَنَّةِ وَأَهْلُ النَّارِ

http://dailyhadith.abuaminaelias.com/2011/04/03/allah-has-revealed-the-people-should-be-humble/