I heard Anas saying, "We traveled with the Prophet (ﷺ) from Medina to Mecca and offered two rak`at (for every prayer) till we returned to Medina." I said, "Did you stay for a while in Mecca?" He replied, "We stayed in Mecca for ten days."
Sahih al-Bukhari Book 18, Hadith 2
← Previous Hadith The Prophet (ﷺ) once stayed for nineteen days and prayed shortened prayers. So when we travel led (and stayed) for nineteen days, we used to shorten the prayer but if we traveled (and stayed) for a longer period we used to offer the full prayer.

Sahih al-Bukhari Book 18, Hadith 1 Next Hadith → 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.

Sahih al-Bukhari Book 18, Hadith 3