Sunan an-Nasai Book 38, Hadith 4135

أَخْبَرَنَا عَمْرُو بْنُ يَحْيَى، قَالَ حَدَّثَنَا مَحْبُوبٌ، - يَعْنِي ابْنَ مُوسَى - قَالَ أَنْبَأَنَا أَبُو إِسْحَاقَ، - وَهُوَ الْفَزَارِيُّ - عَنِ الأَوْزَاعِيِّ، قَالَ كَتَبَ عُمَرُ بْنُ عَبْدِ الْعَزِيزِ إِلَى عُمَرَ بْنِ الْوَلِيدِ كِتَابًا فِيهِ وَقَسْمُ أَبِيكَ لَكَ الْخُمُسُ كُلُّهُ وَإِنَّمَا سَهْمُ أَبِيكَ كَسَهْمِ رَجُلٍ مِنَ الْمُسْلِمِينَ وَفِيهِ حَقُّ اللَّهِ وَحَقُّ الرَّسُولِ وَذِي الْقُرْبَى وَالْيَتَامَى وَالْمَسَاكِينِ وَابْنِ السَّبِيلِ فَمَا أَكْثَرَ خُصَمَاءَ أَبِيكَ يَوْمَ الْقِيَامَةِ فَكَيْفَ يَنْجُو مَنْ كَثُرَتْ خُصَمَاؤُهُ وَإِظْهَارُكَ الْمَعَازِفَ وَالْمِزْمَارَ بِدْعَةٌ فِي الإِسْلاَمِ وَلَقَدْ هَمَمْتُ أَنْ أَبْعَثَ إِلَيْكَ مَنْ يَجُزُّ جُمَّتَكَ جُمَّةَ السُّوءِ ‏.‏

It was narrated that Al-Awza'i said:"Umar bin 'Abdul-'Aziz wrote a letter to 'Umar bin Al-Walid in which he said: 'The share that your father gave to you was the entire Khumus,[1] but the share that your father is entitled to is the same as that of any man among the Muslims, on which is due the rights of Allah and His Messenger, and of relatives, orphans, the poor and wayfarers. How many will dispute with your father on the Day of Resurrection! How can he be saved who has so many disputants? And your openly allowing musical instruments and wind instruments is an innovation in Islam. I was thinking of sending someone to you who would cut off your evil long hair