It is narrated from Hazrat Salim bin Abdullah that Sayyiduna Abdullah bin Umar (may Allah be pleased with them) used to say: I perform shortened (qasr) prayer as long as I do not intend to settle, even if I stay for twelve nights.
Hadith Referenceموطا امام مالك رواية يحييٰ / كتاب قصر الصلاة في السفر / 343