When there are three persons, one of them should lead them. The one among them most worthy to act as Imam is one who is best versed in the Qur'an.  

قَالَ رَسُولُ اللَّهِ ﷺ إِذَا كَانُوا ثَلاَثَةً فَلْيَؤُمَّهُمْ أَحَدُهُمْ وَأَحَقُّهُمْ بِالإِمَامَةِ أَقْرَؤُهُمْ  

A hadith like this has been narrated by Qatida with the same chain of transmitters.  

عَنْ قَتَادَةَ بِهَذَا الإِسْنَادِ مِثْلَهُ  

This hadith has been narrated by Abu Sa'id al-Khudri by another chain of transmitters.  

عَنِ النَّبِيِّ ﷺ بِمِثْلِهِ  

The one who is most versed in Allah's Book should act as Imam for the people, but If they are equally versed in reciting it, then the one who has most knowledge regarding Sunnah if they are equal regarding the Sunnah, then the earliest one to emigrate; it they emigrated at the same time, then the earliest one to embrace Islam. No man must lead another in prayer where (the latter) has authority, or sit in his place of honour in his house, without his permission. Ashajj in his narration used the word," age" in place of" Islam".  

قَالَ رَسُولُ اللَّهِ ﷺ يَؤُمُّ الْقَوْمَ أَقْرَؤُهُمْ لِكِتَابِ اللَّهِ فَإِنْ كَانُوا فِي الْقِرَاءَةِ سَوَاءً فَأَعْلَمُهُمْ بِالسُّنَّةِ فَإِنْ كَانُوا فِي السُّنَّةِ سَوَاءً فَأَقْدَمُهُمْ هِجْرَةً فَإِنْ كَانُوا فِي الْهِجْرَةِ سَوَاءً فَأَقْدَمُهُمْ سِلْمًا وَلاَ يَؤُمَّنَّ الرَّجُلُ الرَّجُلَ فِي سُلْطَانِهِ وَلاَ يَقْعُدْ فِي بَيْتِهِ عَلَى تَكْرِمَتِهِ إِلاَّ بِإِذْنِهِ قَالَ الأَشَجُّ فِي رِوَايَتِهِ مَكَانَ سِلْمًا سِنًّا  

A hadith like this has been narrated by A'mash by the same chain of transmitters  

عَنِ الأَعْمَشِ بِهَذَا الإِسْنَادِ مِثْلَهُ  

The Messenger of Allah ﷺ said to us: The one who is well grounded in Allah's Book and is distinguished among them in recitation should act as; Imam for the people. and if they are equally versed in reciting it, then the one who has most knowledge regarding Sunnah; if they are equal regarding the Sunnah, then the earliest one to emigrate; If they emigrated at the same time, then the oldest one in age. No man must lead another in prayer in latter's house or where (the latter) has authority, or sit in his place of honour in his house, except that he gives you permission or with his permission.  

لَنَا رَسُولُ اللَّهِ ﷺ يَؤُمُّ الْقَوْمَ أَقْرَؤُهُمْ لِكِتَابِ اللَّهِ وَأَقْدَمُهُمْ قِرَاءَةً فَإِنْ كَانَتْ قِرَاءَتُهُمْ سَوَاءً فَلْيَؤُمَّهُمْ أَقْدَمُهُمْ هِجْرَةً فَإِنْ كَانُوا فِي الْهِجْرَةِ سَوَاءً فَلْيَؤُمَّهُمْ أَكْبَرُهُمْ سِنًّا وَلاَ تَؤُمَّنَّ الرَّجُلَ فِي أَهْلِهِ وَلاَ فِي سُلْطَانِهِ وَلاَ تَجْلِسْ عَلَى تَكْرِمَتِهِ فِي بَيْتِهِ إِلاَّ أَنْ يَأْذَنَ لَكَ أَوْ بِإِذْنِهِ  

We came to the Messenger of Allah ﷺ and we were all young men of nearly equal age. We stayed with him (the Holy Prophet) for twenty nights, and as the Messenger of Allah ﷺ was extremely kind and tender of heart, he therefore, thought that we were eager (to see) our family (we felt homesick). So he asked us about the members of the family that we had left behind and when we informed him, he said: Go back to your family, stay with them, and teach them (beliefs and practices of Islam) and exhort them to good, and when the time for prayer comes, one amongst you should announce Adhan and then the oldest among you should lead the prayer.  

أَتَيْنَا رَسُولَ اللَّهِ ﷺ وَنَحْنُ شَبَبَةٌ مُتَقَارِبُونَ فَأَقَمْنَا عِنْدَهُ عِشْرِينَ لَيْلَةً وَكَانَ رَسُولُ اللَّهِ ﷺ رَحِيمًا رَقِيقًا فَظَنَّ أَنَّا قَدِ اشْتَقْنَا أَهْلَنَا فَسَأَلَنَا عَنْ مَنْ تَرَكْنَا مِنْ أَهْلِنَا فَأَخْبَرْنَاهُ فَقَالَ ارْجِعُوا إِلَى أَهْلِيكُمْ فَأَقِيمُوا فِيهِمْ وَعَلِّمُوهُمْ وَمُرُوهُمْ فَإِذَا حَضَرَتِ الصَّلاَةُ فَلْيُؤَذِّنْ لَكُمْ أَحَدُكُمْ ثُمَّ لْيَؤُمَّكُمْ أَكْبَرُكُمْ  

This hadith has been transmitted by Ayyub with the same chain of narrator.  

عَنْ أَيُّوبَ بِهَذَا الإِسْنَادِ  

I came to the Messenger of Allah ﷺ along with other persons and we were young men of nearly equal age, and the rest of the hadith was transmitted like the hadith narrated before.  

أَتَيْتُ رَسُولَ اللَّهِ ﷺ فِي نَاسٍ وَنَحْنُ شَبَبَةٌ مُتَقَارِبُونَ وَاقْتَصَّا جَمِيعًا الْحَدِيثَ بِنَحْوِ حَدِيثِ ابْنِ عُلَيَّةَ  

I came to the Messenger of Allah ﷺ along with a companion of mine, and when we intended to return from him, he said: When there is time for prayer, announce prayer, pronounce Iqama, and the oldest amongst you should lead the prayer.  

أَتَيْتُ النَّبِيَّ ﷺ أَنَا وَصَاحِبٌ لِي فَلَمَّا أَرَدْنَا الإِقْفَالَ مِنْ عِنْدِهِ قَالَ لَنَا إِذَا حَضَرَتِ الصَّلاَةُ فَأَذِّنَا ثُمَّ أَقِيمَا وَلْيَؤُمَّكُمَا أَكْبَرُكُمَا  

" They both were equal in recitation."  

الْحَذَّاءُ وَكَانَا مُتَقَارِبَيْنِ فِي الْقِرَاءَةِ