The Book of al-Bay'ah
39/37. Chapter:
The Virtue Of The One Who Speaks The Truth Before An Unjust Ruler
Sunan an-Nasai
أَخْبَرَنَا إِسْحَاقُ بْنُ مَنْصُورٍ، قَالَ حَدَّثَنَا عَبْدُ الرَّحْمَنِ، عَنْ سُفْيَانَ، عَنْ عَلْقَمَةَ بْنِ مَرْثَدٍ، عَنْ طَارِقِ بْنِ شِهَابٍ، أَنَّ رَجُلاً، سَأَلَ النَّبِيَّ صلى الله عليه وسلم وَقَدْ وَضَعَ رِجْلَهُ فِي الْغَرْزِ أَىُّ الْجِهَادِ أَفْضَلُ قَالَ " كَلِمَةُ حَقٍّ عِنْدَ سُلْطَانٍ جَائِرٍ " .
It was narrated from Tariq bin Shihab that: a man asked the Prophet, when he had put his leg in the stirrup: "Which kind of Jihad is best?'" He said: " a word of truth spoken before an unjust rulers."
Reference : Sunan an-Nasa'i 4209In-book reference : Book 39, Hadith 61English translation : Vol. 5, Book 39, Hadith 4214