Umar on Injustice: Supplication of oppressed always answered

Malik ibn Anas reported: Umar ibn al-Khattab, may Allah be pleased with him, said, “Beware of the supplication of the oppressed, for the supplication of the oppressed is answered.”

Source: al-Muwaṭṭa’ 1890

عن مالك بن أنس قال عمر بن الخطاب رضي الله عنه وَاتَّقِ دَعْوَةَ الْمَظْلُومِ فَإِنَّ دَعْوَةَ الْمَظْلُومِ مُجَابَةٌ

1890 موطأ مالك كتاب الجامع