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. (Using translation from Bukhārī 1082)
صَلَّيْتُ مَعَ النَّبِيِّ ﷺ بِمِنًى رَكْعَتَيْنِ وَمَعَ أَبِي بَكْرٍ وَمَعَ عُمَرَ وَعُثْمَانَ صَدْرًا مِنْ إِمَارَتِهِ ثُمَّ أَتَمَّ