Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) says: "Whoever builds in the lands of the non-Arabs, celebrates their Nayruz and Mihrajan festivals and imitates them until he dies in that state, will be gathered with them on the Day of Resurrection."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18863