question #1 Sahih al-Bukhari 1090, Book 18, Hadith 11 : How did the number of rak`at in prayers change for travelers and non-travelers over time?

“When the prayers were first enjoined they were of two rak`at each. Later the prayer in a journey was
kept as it was but the prayers for non-travelers were completed.” Az-Zuhri said, “I asked `Urwa what
made Aisha pray the full prayers (in journey).” He replied, “She did the same as `Uthman did.”