The Messenger of Allah ﷺ led us in the dawn prayer one day. And he said: Is so and so present? They said: No. He (again) asked: Is so and so present? They replied: No. He then said: These two prayers are the ones which are most burdensome to hypocrites. If you knew what they contain (i.e. blessings), you would come to them, even though you had to crawl on your knees. The first row is like that of the angels, and if you knew the nature of its excellence, you would race to join it. A man's prayer said along with another is purer than his prayer said alone, and his prayer with two men is purer than his prayer with one, but if there are more it is more pleasing to Allah, the Almighty, the Majestic. (Using translation from Abū Dāʾūd 554)
أَنَّهُ قَالَ صَلَّى رَسُولُ اللهِ ﷺ الصُّبْحَفَقَالَ شَاهِدٌ فُلَانٌ؟ فَقَالُوا لَا فَقَالَ شَاهِدٌ فُلَانٌ؟ فَقَالُوا لَا فَقَالَ شَاهِدٌ فُلَانٌ فَقَالُوا لَا فَقَالَ إِنَّ هَاتَيْنِ الصَّلَاتَيْنِ مِنْ أَثْقَلِ الصَّلَوَاتِ عَلَى الْمُنَافِقِينَ وَلَوْ يَعْلَمُونَ مَا فِيهِمَا لَأَتَوْهُمَا وَلَوْ حَبْوًا وَالصَّفُّ الْمُقَدَّمُ عَلَى مِثْلِ صَفِّ الْمَلَائِكَةِ وَلَوْ تَعْلَمُونَ فَضِيلَتَهُ لَابْتَدَرْتُمُوهُ وَصَلَاةُ الرَّجُلِ مَعَ الرَّجُلَ أَزْكَى مِنْ صَلَاتِهِ وَحْدَهُ وَصَلَاتُهُ مَعَ رَجُلَيْنِ أَزْكَى مِنْ صَلَاتِهِ مَعَ رَجُلٍ وَمَا كَانَ أَكْثَرَ فَهُوَ أَحَبُّ إِلَى اللهِ