Question: When did Abu Bakr stop being Rashidun Caliphate?
Paraphrase: On what date did Abu Bakr cease to be Rashidun Caliphate?
SPARQL (Wikidata): SELECT ?value WHERE { wd:Q334923 p:P39 ?s . ?s ps:P39 wd:Q12490507 . ?s pq:P582 ?value}