"Urwah told me that 'Aishah said: 'Allah enjoined the salah upon the Messenger of Allah (ﷺ), and the first thing that He enjoined was two Rak'ahs at a time, then it was made complete four Rak'ahs while in the state of residence but the prayer when traveling remained two Rak'ahs, as it was first enjoined.'"
Sunan an-Nasa'i Book 5, Hadith 7
← Previous Hadith "The first time the Salah was enjoined it was two Rak'ahs, and it remained as such when traveling, but the Salah while resident was made complete."

Sunan an-Nasa'i Book 5, Hadith 6 Next Hadith → "The Salah was enjoined two Rak'ahs at a time, then the Salah when traveling remained like that, but the Salah while resident was increased."

Sunan an-Nasa'i Book 5, Hadith 8