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  

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 (may peace be upon hiin) used to say: The supplication of a Muslim for his brother at his back (in his absence) is responded so long as he makes a supplica- tion for blessings for his brother and the commissioned Angel says: Amen, and says: May it be for you too I I went to the bazar and met Abfi Dardi' and he narrated like this from Messenger of Allah ﷺ. (Using translation from Muslim 2733)   

أَتَيْتُ الشَّامَ فَدَخَلْتُ عَلَى أَبِي الدَّرْدَاءِ فَلَمْ أَجِدْهُ وَوَجَدْتُ أُمَّ الدَّرْدَاءِ فَقَالَتْ تُرِيدُ الْحَجَّ الْعَامَ؟ قَالَ قُلْتُ نَعَمْ فَقَالَتْ فَادْعُ لَنَا بِخَيْرٍ فَإِنَّ النَّبِيَّ ﷺ كَانَ يَقُولُ إِنَّ دَعْوَةَ الْمُسْلِمِ مُسْتَجَابَةٌ لِأَخِيهِ بِظَهْرِ الْغَيْبِ عِنْدَ رَأْسِهِ مَلَكٌ مُوَكَّلٌ كُلَّمَا دَعَا لِأَخِيهِ بِخَيْرٍ قَالَ آمِينَ وَلَكَ بِمِثْلٍ فَخَرَجْتُ إِلَى السُّوقِ فَأَلْقَى أَبَا الدَّرْدَاءِ فَقَالَ لِي مِثْلَ ذَلِكَ يَأْثُرُهُ عَنِ النَّبِيِّ ﷺ  

[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