It is narrated from Ibn Abbas (may Allah be pleased with them) that he said: Prayer will be shortened up to ‘Usfan, Ta’if, and Jeddah. And all these places are at a distance of four barid from Makkah, and similarly, prayer will be shortened in places at such a distance.
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 351