Imam Ahmad : 4065

حَدَّثَنَا عَبْدُ الرَّزَّاقِ أَخْبَرَنَا إِسْرَائِيلُ عَنْ سِمَاكٍ عَنْ عَبْدِ الرَّحْمَنِ بْنِ عَبْدِ اللَّهِ عَنْ أَبِيهِ قَالَ قَالَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مَنْ أَعَانَ قَوْمَهُ عَلَى ظُلْمٍ فَهُوَ كَالْبَعِيرِ الْمُتَرَدِّي يَنْزِعُ بِذَنَبِهِ

Narrated to us [Abdurrazaq] had told us [Isra`il] from [Simak] from [Abdurrahman bin Abdullah] from [his father] he said: The Prophet sallallaahu 'alaihi wasallam said: "Whoever helps the injustice of his people, he is like a camel that fell from a high place and was picked up by its tail.