Hadith on Dua: No barrier between Allah and two supplications

Ibn Abbas reported: The Messenger of Allah, peace and blessings be upon him, said, “Two supplications have no barrier between them and Allah: the supplication of the oppressed, and the supplication of a man for his brother behind his back.

Source: al-Mu’jam al-Kabīr 11232

Grade: Sahih (authentic) according to Al-Suyuti

عَنِ ابْنِ عَبَّاسٍ قَالَ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ دَعْوَتَانِ لَيْسَ بَيْنَهُمَا وَبَيْنَ اللَّهِ حِجَابٌ دَعْوَةُ الْمَظْلُومِ وَدَعْوَةُ الْمَرْءِ لِأَخِيهِ بِظَهْرِ الْغَيْبِ

11232 المعجم الكبير للطبراني

4191 المحدث السيوطي خلاصة حكم المحدث صحيح في الجامع الصغير