Aslam, the freed slave of Umar bin al-Khattab (may Allah be pleased with him), said that Umar bin al-Khattab (may Allah be pleased with him) allowed the Jews, the Christians and the Magians a stay of three days in Madinah to trade in the markets. They would also see to their needs. No one was permitted to stay beyond three days.
Note: Imam al-Shafi'i (may Allah have mercy on him) said in his old (school), and gave the same answer in his new (school): Whoever resolves to stay four days is to pray the complete prayer. And several hadiths have been narrated to me about this, among them one from Qatadah, from Sayyiduna Uthman bin Affan (may Allah be pleased with him), to the same effect.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5454