Thanks for the scanned document. One note is that the document mentions that John's father Isaac B Smith was from Smith [sic], VA. This could not be completly accurate. From http://www.smythcounty.org/
"on February 23, 1832, the Virginia General Assembly created Smyth County from parts of Washington and Wythe Counties." If Isaac B. died circa 1801 he could not have been from Smyth County. Perhaps he lived in a section of Washington or Wythe Counties that at the time the document was written was (is) encompassed by Smyth Co. On my tree I have Elder John as being born in Washington Co (Va or Tn). With this new information it seems likely that Washington Co. VA is correct.