Sunan Abi Dawud 5117
سنن أبي داود#5117Sahihحَدَّثَنَا النُّفَيْلِيُّ، حَدَّثَنَا زُهَيْرٌ، حَدَّثَنَا سِمَاكُ بْنُ حَرْبٍ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ، عَنْ أَبِيهِ، قَالَ مَنْ نَصَرَ قَوْمَهُ عَلَى غَيْرِ الْحَقِّ فَهُوَ كَالْبَعِيرِ الَّذِي رُدِّيَ فَهُوَ يُنْزَعُ بِذَنَبِهِ .
Narrated Abdullah ibn Mas'ud: If anyone helps his people in an unrighteous cause, he is like a camel which falls into a well and is pulled out by its tail
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Al-AlbaniSahih Muquf
Muhammad Muhyi Al-Din Abdul HamidSahih Muquf
Zubair Ali ZaiIsnaad Sahih
In-book reference: 43:345