At the beginning of every century Allah will send to this ummah someone who will renew its religious understanding.” Narrated by Abu Dawood (4291); classed as saheeh by as-Sakhkhaawi in al-Maqaasid al-Hasanah (149) and by al-Albaani in as-Silsilah as-Saheehah (no. 599).
Does the counting starts after death of prophet? Or after end of raashidun caliphate?
I'm asking this because during siege of kaaba in 80's they used the above hadith and the day was muharram 1, 1400 hijri and declared a person named muhammad as mahdi