While there's nothing inherently bad about Sunday in Islam, Friday is the special day of worship in Islam, not Sunday.
Although Sunday isn't designated as a specific day for religious observance, activities permissible on any other day are also permissible on Sunday. There's no prohibition against working, engaging in leisure, or conducting normal daily affairs on Sunday. The distinction lies in Friday's importance for congregational prayer (Jumu'ah).
In summary, while Sunday isn't religiously significant like Friday, it's considered a regular day with no restrictions or special requirements in Islam.
