Angels make dua for the one who makes dua for this brother

that he heard the Messenger of Allah ﷺ say, “He who supplicates for his brother behind his back (in his absence), the representative Angel [assigned] to him says: Amen, and it is for you also.”

أَنَّهُ سَمِعَ رَسُولَ اللَّهِ ﷺ يَقُولُ: «مَنْ دَعَا لأَخِيهِ بِظَهْرِ الْغَيْبِ، قَالَ الْمَلَكُ الْمُوَكَّلُ بِهِ: آمِينَ وَلَكَ بِمِثْلٍ»