Sahih Muslim 649 f
Abu Huraira reported Allah's Messenger (ﷺ) as saying:
A man's prayer in congregation is more valuable than twenty degrees and some above them as compared with his prayer in his house and his market, for when he performs ablution doing it well, then goes out to the mosque, and he is impelled (to do so) only by (the love of congregational) prayer, he has no other objective before him but prayer. He does not take a step without being raised a degree for it and having a sin remitted for it, till he enters the mosque, and when he is busy in prayer after having entered the mosque. the angels continue to invoke blessing on him as long as he is in his place of worship. saying: O Allah, show him mercy, and pardon him! Accept his repentance (and the angels continue this supplication for him) so long as he does not do any harm in it, or as long as his ablution is not broken.
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَأَبُو كُرَيْبٍ جَمِيعًا عَنْ أَبِي مُعَاوِيَةَ، - قَالَ أَبُو كُرَيْبٍ حَدَّثَنَا أَبُو مُعَاوِيَةَ، - عَنِ الأَعْمَشِ، عَنْ أَبِي صَالِحٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏
"‏ صَلاَةُ الرَّجُلِ فِي جَمَاعَةٍ تَزِيدُ عَلَى صَلاَتِهِ فِي بَيْتِهِ وَصَلاَتِهِ فِي سُوقِهِ بِضْعًا وَعِشْرِينَ دَرَجَةً وَذَلِكَ أَنَّ أَحَدَهُمْ إِذَا تَوَضَّأَ فَأَحْسَنَ الْوُضُوءَ ثُمَّ أَتَى الْمَسْجِدَ لاَ يَنْهَزُهُ إِلاَّ الصَّلاَةُ لاَ يُرِيدُ إِلاَّ الصَّلاَةَ فَلَمْ يَخْطُ خَطْوَةً إِلاَّ رُفِعَ لَهُ بِهَا دَرَجَةٌ وَحُطَّ عَنْهُ بِهَا خَطِيئَةٌ حَتَّى يَدْخُلَ الْمَسْجِدَ فَإِذَا دَخَلَ الْمَسْجِدَ كَانَ فِي الصَّلاَةِ مَا كَانَتِ الصَّلاَةُ هِيَ تَحْبِسُهُ وَالْمَلاَئِكَةُ يُصَلُّونَ عَلَى أَحَدِكُمْ مَا دَامَ فِي مَجْلِسِهِ الَّذِي صَلَّى فِيهِ يَقُولُونَ اللَّهُمَّ ارْحَمْهُ اللَّهُمَّ اغْفِرْ لَهُ اللَّهُمَّ تُبْ عَلَيْهِ مَا لَمْ يُؤْذِ فِيهِ مَا لَمْ يُحْدِثْ فِيهِ ‏"‏ ‏.‏