This is because Allah would never change His favor that He bestowed upon a nation until they change what is in their hearts. Allah is Hearing, Knowing.
"Wancan ne, dõmin lalle ne, Allah bai kasance Mai canza wata ni'ima wadda ya ni'imtar da ita a kan wasu mutãne ba fãce sun sãke abin da yake ga rãyukansu, kuma dõmin lalle Allah ne Mai jĩ, Masani."