BUKHARI 2448:
from Yaḥyá —
The Prophet ﷺ sent Muʿadh to Yemen and said, "Be afraid, from the curse of the oppressed as there is no screen between his invocation and Allah."
البخاري ٢٤٤٨:
عن يحيى —
أَنَّ النَّبِيَّ ﷺ بَعَثَ مُعَاذًا إِلَى الْيَمَنِ فَقَالَ: «اتَّقِ دَعْوَةَ الْمَظْلُومِ، فَإِنَّهَا لَيْسَ بَيْنَهَا وَبَيْنَ اللَّهِ حِجَابٌ۔»