Yahya related to me from Malik from Ibn Shihab from Salim ibnAbdullah that Abdullah ibn Umar used to say, "I pray the prayerof atraveller as long as I am undecided whether to remain somewhere ornot, even if I am detained for twelve nights." (RU)
USC-MSA web (English) reference: Book 9, Hadith 18 (RU)
Arabic reference (RU): Book 9, Hadith 346 (RU)