It wasnarrated that Ibn 'Abbas said:
"Allah enjoined the prayer uponthe tongue of your Prophet (ﷺ): Four Rak'ah while a resident andtwoRak'ah when traveling." (RU)
English reference (RU): Vol. 1, Book 5, Hadith 1068 (RU)
Arabic reference (RU): Book 5, Hadith 1121 (RU)