It is narrated from Sayyiduna Sahl that the Prophet (peace and blessings be upon him) said: If a person witnesses a believer being humiliated in his presence and, despite having the power, does not help him, Allah Almighty will humiliate him before all of creation on the Day of Resurrection.
Hadith Referenceمسند احمد / مسند المكيين / 15985
Hadith Gradingحکم دارالسلام:إسناده ضعيف لضعف ابن لهيعة، وموسي بن جبير الأنصاري مستور