question #3 Sahih Muslim 685b, Book 6, Hadith 2 : How does the prescription of prayer differ between a place of residence and during a journey?

‘A’isha, the wife of the Messenger of Allah (ﷺ), said Allah prescribed the prayer as two rak’ahs, then it was completed (to four rak’ahs) at the place of residence, but was retained in the same position in journey as it was first made obligatory.