I visited Abu Darda's house in Syria. I did not find him there but Umm Darda' (was present at the house). She said: Do you intend to perform Hajj during this year? I said: Yes. She said: Do supplicate Allah for blessings upon us...

for Allah's Apostle ﷺ used to say: The supplication of a Muslim for his brother in his absence is responded to. An angel is commissioned next to him. Every time he prays for good for his brother, the commissioned Angel says: Āmīn, and says: May it be for you too.

I then went to the bazar and met Abū Dardāʾ and he narrated like this from Prophet ﷺ.  

قَدِمْتُ الشَّامَ فَأَتَيْتُ أَبَا الدَّرْدَاءِ فِي مَنْزِلِهِ فَلَمْ أَجِدْهُ وَوَجَدْتُ أُمَّ الدَّرْدَاءِ فَقَالَتْ أَتُرِيدُ الْحَجَّ الْعَامَ فَقُلْتُ نَعَمْ قَالَتْ فَادْعُ اللَّهَ لَنَا بِخَيْرٍ

فَإِنَّ النَّبِيَّ ﷺ كَانَ يَقُولُ «دَعْوَةُ الْمَرْءِ الْمُسْلِمِ لأَخِيهِ بِظَهْرِ الْغَيْبِ مُسْتَجَابَةٌ عِنْدَ رَأْسِهِ مَلَكٌ مُوَكَّلٌ كُلَّمَا دَعَا لأَخِيهِ بِخَيْرٍ قَالَ الْمَلَكُ الْمُوَكَّلُ بِهِ آمِينَ وَلَكَ بِمِثْلٍ۔»

قَالَ فَخَرَجْتُ إِلَى السُّوقِ فَلَقِيتُ أَبَا الدَّرْدَاءِ فَقَالَ لِي مِثْلَ ذَلِكَ يَرْوِيهِ عَنِ النَّبِيِّ ﷺ  

“Do you intend to perform Hajj this year?” He said: “Yes.” She said: “Pray to Allah for us to grant us goodness, for the Prophet ﷺ used to say: ‘The supplication of a man for his brother in his absence will be answered. By his head there is an angel who says Amin to his supplication, and every time he prays for his brother, he says: “Amin, and the same for you.’” He said: “Then I went out to the marketplace where I met Abu Darda’, and he told me something similar from the Prophet ﷺ.”  

وَكَانَتْ تَحْتَهُ ابْنَةُ أَبِي الدَّرْدَاءِ فَأَتَاهَا فَوَجَدَ أُمَّ الدَّرْدَاءِ وَلَمْ يَجِدْ أَبَا الدَّرْدَاءِ فَقَالَتْ لَهُ تُرِيدُ الْحَجَّ الْعَامَ قَالَ نَعَمْ قَالَتْ فَادْعُ اللَّهَ لَنَا بِخَيْرٍ فَإِنَّ النَّبِيَّ ﷺ كَانَ يَقُولُ دَعْوَةُ الْمَرْءِ مُسْتَجَابَةٌ لأَخِيهِ بِظَهْرِ الْغَيْبِ عِنْدَ رَأْسِهِ مَلَكٌ يُؤَمِّنُ عَلَى دُعَائِهِ كُلَّمَا دَعَا لَهُ بِخَيْرٍ قَالَ آمِينَ وَلَكَ بِمِثْلِهِ قَالَ ثُمَّ خَرَجْتُ إِلَى السُّوقِ فَلَقِيتُ أَبَا الدَّرْدَاءِ فَحَدَّثَنِي عَنِ النَّبِيِّ ﷺ بِمِثْلِ ذَلِكَ  

[Machine] "Pray for us for good, for verily the Prophet ﷺ used to say that the supplication of a Muslim for his brother in his absence is answered. Above his head is an appointed angel whenever he supplicates for his brother with a good, saying: 'Amen, and may you have the same.' I then went out to the market and I met Abu Darda who informed me about the Prophet ﷺ with the same."  

فَادْعُ لَنَا بِخَيْرٍ فَإِنَّ النَّبِيَّ ﷺ كَانَ يَقُولُ إِنَّ دَعْوَةَ الْمَرْءِ الْمُسْلِمِ مُسْتَجَابَةٌ لِأَخِيهِ بِظَهْرِ الْغَيْبِ عِنْدَ رَأْسِهِ مَلَكٌ مُوَكَّلٌ بِهِ كُلَّمَا دَعَا لِأَخِيهِ بِخَيْرٍ قَالَ آمِينَ وَلَكَ بِمِثْلٍ قَالَ فَخَرَجْتُ إِلَى السُّوقِ فَلَقِيتُ أَبَا الدَّرْدَاءِ فَحَدَّثَنِي عَنِ النَّبِيِّ ﷺ بِمِثْلِ ذَلِكَ  

[Machine] "Invoke Allah for us with good, for indeed the Prophet ﷺ used to say, 'Verily, the supplication of the oppressed is answered for his brother in the unseen, by an angel who supports him upon his supplication, whenever he supplicates for him with good, he says: "Ameen, and for you the same."' He said, 'Then I went out to the market and I met Abu Darda and he told me about the Prophet ﷺ similarly.'"  

ادْعُ اللهَ لَنَا بِخَيْرٍ فَإِنَّ النَّبِيَّ ﷺ كَانَ يَقُولُ «إِنَّ دَعْوَةَ الْمَظْلُومِ مُسْتَجَابَةٌ لِأَخِيهِ بِظَهْرِ الْغَيْبِ عِنْدَ رَأْسَهِ مَلَكٌ يُؤَمِّنُ عَلَى دُعَائِهِ كُلَّمَا دَعَا لَهُ بِخَيْرٍ قَالَ آمِينَ وَلَكَ بِمِثْلٍ» قَالَ ثُمَّ خَرَجْتُ إِلَى السُّوقِ فَلَقِيتُ أَبَا الدَّرْدَاءِ فَحَدَّثَنِي عَنِ النَّبِيِّ ﷺ بِمِثْلِهِ