the believers are those only who believe in allah and his messenger and afterward doubt not but strive with their wealth and their lives for the cause of allah. such are the sincere.
إنما المؤمنون الذين آمنوا بالله ورسوله ثم لم يرتابوا وجاهدوا بأموالهم وأنفسهم في سبيل الله أولئك هم الصادقون