what is the origin of saying radhiAllahu anhu after sahaba and salalaahu alaihi wa sallam after mentioning the prophet? did the sahaba begin saying رضي الله عنه after the death of their fellow companions?
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it is generally them most common salawat sent when rasoolullah is mentioned along with salawatullahi alai which i think mostly arabs say. which darood did the sahaba say when mentioning the prophet? also whilst the prophet was alive did they only say ya rasoolullah or did they also say a darood afterwards and then say what they had to say? 
