Uthman bin Abi Shaybah narrated it from Abu Mu'awiyah, who said: The Messenger of Allah (peace and blessings be upon him) travelled and stayed seventeen days, and he (peace and blessings be upon him) kept praying two rak'ahs each.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5464