It wasnarrated that Ibn 'Abbas and Ibn 'Umar said:
"The Messenger ofAllah (ﷺ) prescribed two Rak'ah of prayer when traveling; theyarecomplete and are not shortened. And Witr when traveling isSunnah." (ID)
English reference (ID): Vol. 1, Book 5, Hadith 1194 (ID)
Arabic reference (ID): Book 5, Hadith 1250 (ID)