question #1 Sahih al-Bukhari 1082, Book 18, Hadith 3 : How did the practice of shortening prayers during travel evolve among the early caliphs?

I offered the prayer with the Prophet, Abu Bakr and `Umar at Mina and it was of two rak`at. `Uthman
in the early days of his caliphate did the same, but later on he started praying the full prayer.