Hazrat Saeed bin Musayyib used to say that whoever intends to stay for four nights should perform the full prayer. Imam Malik, may Allah have mercy on him, said: I like this.
Imam Malik, may Allah have mercy on him, was asked about the prayer of a prisoner. He replied that the prisoner should pray like a resident, but if he is a traveler, then he should shorten the prayer.
Hadith Referenceموطا امام مالك رواية يحييٰ / كتاب قصر الصلاة في السفر / 345