[Machine] The Prophet ﷺ sent Mu'adh ibn Jabal to Yemen and said to him at the end of his instructions, "Beware of the supplication of the oppressed, for there is no barrier between it and Allah." This hadith is reported by Bukhari and Muslim in Sahih from the narration of Waki' and others.
أَنَّ النَّبِيَّ ﷺ بَعَثَ مُعَاذَ بْنَ جَبَلٍ ؓ إِلَى الْيَمَنِ الْحَدِيثَ وَقَالَ فِي آخِرِهِ وَاتَّقِ دَعْوَةَ الْمَظْلُومِ؛ فَإِنَّهُ لَيْسَ بَيْنَهَا وَبَيْنَ اللهِ حِجَابٌ وَأَخْرَجَهُ الْبُخَارِيُّ وَمُسْلِمٌ فِي الصَّحِيحِ مِنْ حَدِيثِ وَكِيعٍ وَغَيْرِهِ