Line in the sand is an idiom, a metaphorical (sometimes literal) point beyond which no further advance will be accepted or made. Related terms include unilateral boundary setting, red lines and ultimatums to define clear consequences if a line is crossed.

Origin

Biblical link to John 8 (John 8:6). Some have (perhaps erroneously) interpreted Jesus' writing in the sand, as drawing a line in the sand in order to address those who are about to stone a woman caught in adultery. However, the literal translation is not that he drew a line in the sand, but that he "wrote" (or "drew lines" in some translations) in the sand, an important distinction. The exact origin of the phrase is unknown: the Oxford English Dictionary suggests a transitional use from 1950, but a definitely figurative use only as late as 1978: "He drew a line in the sand with the toe of his boot, and said, 'It's as though I told you "I can punch you in the nose, but you can't reach across that line to hit me back."'"

• The Washington Post, 19 December 1950 "Notwithstanding the supposed public revulsion toward more federal spending, waste and bureaucracy-building, Congress seems to have gone out of its way to draw a wide line in the sand in front of Carter."
• The Washington Post, 29 October 1978 There is reference to an actual line being drawn in several historical, or legendary, military events:

Recent uses