A stone's throw
A short distance.
A stone's throw is, of course, literally the distance that a stone can be thrown, but has come to mean any short but undefined distance. Early English versions of the Bible refer to 'a stone's cast' with the same meaning, as in Luke 22:41, Wycliffe's Bible, 1526, for example:
in nd he gat himself from them, about a stone's cast,
'Stone's throw' was used in a non-biblical setting by the end of the 16th century. Arthur Hall's translation The Ten books of Homers Iliades, 1581, contains this line:
"For who can see a stones throw of ought thing in land or plaine?"
Stones hadn't then been established as the definitive objects to be thrown and the following year Nicholas Lichefield wrote:
"The enimyes were come, within the throwe of a Dart."
All forms of the phrase were little used and it wasn't until 1704 that Jonathan Swift revived it in The battle of the books:
"The two Cavaliers had now approach'd within a Throw of a Lance."
The 'stone's throw' variant was established properly by John Arbuthnot in The History of John Bull, 1712, and, following that, there are many citations of the phrase.
"Mrs. Bull's condition was looked upon as desperate by all the men of art; but there were those that bragged they had an infallible ointment and plaister, which being applied to the sore, would cure it in a few days; at the same time they would give her a pill that would purge off all her bad humours, sweeten her blood, and rectify her disturbed imagination. In spite of all applications the patient grew worse every day; she stunk so, nobody durst come within a stone's throw of her, except those quacks who attended her close, and apprehended no danger."