Salim b. 'Abdullah (b. 'Umar) reported on the authority of his father that Messenger of Allah ﷺ observed the prayer of a traveller, i. e. two rak'ahs in Mina, and other places; so did Abu Bakr and 'Umar, and 'Uthman too observed two rak'ahs at the beginning of his caliphate, but he then completed four.
عَنْ رَسُولِ اللَّهِ ﷺ أَنَّهُ صَلَّى صَلاَةَ الْمُسَافِرِ بِمِنًى وَغَيْرِهِ رَكْعَتَيْنِ وَأَبُو بَكْرٍ وَعُمَرُ وَعُثْمَانُ رَكْعَتَيْنِ صَدْرًا مِنْ خِلاَفَتِهِ ثُمَّ أَتَمَّهَا أَرْبَعًا
I offered the prayer with the Prophet, Abu Bakr and ʿUmar at Mina and it was of two rakʿat. ʿUthman in the early days of his caliphate did the same, but later on he started praying the full prayer.
صَلَّيْتُ مَعَ النَّبِيِّ ﷺ بِمِنًى رَكْعَتَيْنِ وَأَبِي بَكْرٍ وَعُمَرَ وَمَعَ عُثْمَانَ صَدْرًا مِنْ إِمَارَتِهِ ثُمَّ أَتَمَّهَا
Messenger of Allah ﷺ offered a two-rakʿat prayer at Mina. Abu Bakr, ʿUmar and ʿUthman, (during the early years of his caliphate) followed the same practice.
صَلَّى رَسُولُ اللَّهِ ﷺ بِمِنًى رَكْعَتَيْنِ وَأَبُو بَكْرٍ وَعُمَرُ وَعُثْمَانُ صَدْرًا مِنْ خِلاَفَتِهِ
"I prayed two rak'ahs with the Messenger of Allah ﷺ in Mina, and with Abu Bakr and 'Umar, and two rak'ahs with 'Uthman at the beginning of his Caliphate."
أَنَّهُ قَالَ صَلَّيْتُ مَعَ رَسُولِ اللَّهِ ﷺ بِمِنًى وَمَعَ أَبِي بَكْرٍ وَعُمَرَ رَكْعَتَيْنِ وَمَعَ عُثْمَانَ رَكْعَتَيْنِ صَدْرًا مِنْ إِمَارَتِهِ
[Machine] I prayed the night prayer (Isha) with the Messenger of Allah ﷺ in Mina, two units of prayer. And with Abu Bakr, two units of prayer. And with Umar, two units of prayer. And with Uthman, two units of prayer, separately from his caliphate. Then he completed it after Uthman.
صَلَّيْتُ مَعَ رَسُولِ اللهِ ﷺ صَلَاةَ الْعِشَاءِ بِمِنًى رَكْعَتَيْنِ وَمَعَ أَبِي بَكْرٍ رَكْعَتَيْنِ وَمَعَ عُمَرَ رَكْعَتَيْنِ وَمَعَ عُثْمَانَ رَكْعَتَيْنِ صَدْرًا مِنْ خِلَافَتِهِ ثُمَّ أَتَمَّهَا بَعْدُ عُثْمَانُ
"I prayed two rak'ahs with the Messenger of Allah ﷺ in Mina, and with Abu Bakr and 'Umar, and two rak'ahs with 'Uthman at the beginning of his Caliphate." (Using translation from Nasāʾī 1447)
صَلَّيْتُ مَعَ رَسُولِ اللهِ ﷺ بِمِنًى رَكْعَتَيْنِ وَمَعَ أَبِي بَكْرٍ رَكْعَتَيْنِ وَمَعَ عُمَرَ رَكْعَتَيْنِ وَمَعَ عُثْمَانَ صَدْرًا مِنْ خِلَافَتِهِ ثُمَّ صَلَّاهَا أَرْبَعًا
[Machine] That the Messenger of Allah ﷺ performed two units of prayer in Mina, Abu Bakr performed two units of prayer, Umar performed two units of prayer, and Uthman performed two units of prayer as well. All of this was at the beginning of his caliphate, and then he completed them afterwards.
أَنَّ رَسُولَ اللَّهِ ﷺ صَلَّى بِمِنًى رَكْعَتَيْنِ وَأَبَا بَكْرٍ رَكْعَتَيْنِ وَعُمَرَ رَكْعَتَيْنِ وَعُثْمَانَ رَكْعَتَيْنِ صَدْرًا مِنْ إِمَارَتِهِ ثُمَّ أَتَمَّهَا بَعْدُ
Salim b. 'Abdullah (b. 'Umar) reported on the authority of his father that Messenger of Allah ﷺ observed the prayer of a traveller, i. e. two rak'ahs in Mina, and other places; so did Abu Bakr and 'Umar, and 'Uthman too observed two rak'ahs at the beginning of his caliphate, but he then completed four. (Using translation from Muslim 694a)
«أَنَّ رَسُولَ اللَّهِ ﷺ صَلَّى صَلَاةَ الْمُسَافِرِ بِمِنًى رَكْعَتَيْنِ وَأَبُو بَكْرٍ وَعُمَرُ وَعُثْمَانُ رَكْعَتَيْنِ صَدْرًا مِنْ خِلَافَتِهِ ثُمَّ أَتَمَّهَا أَرْبَعًا»
" عَنِ ابْنِ عُمَرَ قَالَ: صَلَّيْتُ مَعَ رَسُولِ الله ﷺ بِمِنًى رَكعَتَيْنِ، وَمَعَ أَبِى بَكْرٍ رَكْعَتَيْنِ، وَمَعَ عُمَرَ رَكْعَتَيْنِ، وَمَعَ عُثْمَانَ صَدْرًا مِنْ خِلاَفَتِهِ، ثُمَّ صلَّاهَا أَرْبَعًا ".