حَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، أَخْبَرَنَا عِيسَى بْنُ يُونُسَ، حَدَّثَنَا عَبْدُ الْمَلِكِ بْنُ أَبِي، سُلَيْمَانَ عَنْ أَبِي الزُّبَيْرِ، عَنْ صَفْوَانَ، - وَهُوَ ابْنُ عَبْدِ اللَّهِ بْنِ صَفْوَانَ - وَكَانَتْ تَحْتَهُ الدَّرْدَاءُ قَالَ 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 صلى الله عليه وسلم 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 صلى الله عليه وسلم ‏.‏

Safwan (and he was Ibn 'Abdullah b. Safwan, and he had been married to Umm Darda') reported: 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 Allah's Messenger (PBUH). Translation Not Available

Book Ref: Sahih Muslim Book 48 Hadith 6590
Web Ref:  Sahih Muslim Book 35 Hadith 2733, 2732