From Sahih Muslim (Hadith 312):
It is narrated on the authority of Abu Huraira that the Messenger of Allah (ﷺ) said:Verily Allah would make a wind to blow from the side of the Yemen more delicate than silk and would spare none but cause him to die who, in the words of Abu 'Alqama, has faith equal to the weight of a grain; while Abdul-'Aziz said: having faith equal to the weight of a dust particle
Reference: Muslim 312