Sunan Ibn Majah 801
It was narrated that 'Abdullah bin 'Amr said:
"We performed the Maghrib (prayer) with the Messenger of Allah, then those who went back went back, and those who stayed, stayed. Then the Messenger of Allah came back in a hurry, out of breath, with his garment pulled up to his knees, and said: 'Be of good cheer, for your Lord has opened one of the gates of heaven and is boasting of you before the angels, saying: "Look at My slaves; they have fulfilled one obligatory duty and are awaiting another."
حَدَّثَنَا أَحْمَدُ بْنُ سَعِيدٍ الدَّارِمِيُّ، حَدَّثَنَا النَّضْرُ بْنُ شُمَيْلٍ، حَدَّثَنَا حَمَّادٌ، عَنْ ثَابِتٍ، عَنْ أَبِي أَيُّوبَ، عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو، قَالَ صَلَّيْنَا مَعَ رَسُولِ اللَّهِ ـ صلى الله عليه وسلم ـ الْمَغْرِبَ فَرَجَعَ مَنْ رَجَعَ وَعَقَّبَ مَنْ عَقَّبَ فَجَاءَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ مُسْرِعًا قَدْ حَفَزَهُ النَّفَسُ و قَدْ حَسَرَ عَنْ رُكْبَتَيْهِ فَقَالَ ‏
"‏ أَبْشِرُوا هَذَا رَبُّكُمْ قَدْ فَتَحَ بَابًا مِنْ أَبْوَابِ السَّمَاءِ يُبَاهِي بِكُمُ الْمَلاَئِكَةَ يَقُولُ انْظُرُوا إِلَى عِبَادِي قَدْ قَضَوْا فَرِيضَةً وَهُمْ يَنْتَظِرُونَ أُخْرَى ‏"‏ ‏.‏