draw the line at, to

draw a line at (doing) (something)

To set a (figurative) boundary, indicating what one is not willing or able to do. I'm willing to accept some minor edits on my script, but I draw a line at any major rewrites. Aunt Peggy was fine with us setting her up on a date, but she drew a line at letting us create an online dating profile.
See also: draw, line
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

draw the line at

Refuse to go any further than, as in I draw the line at giving them more money. This expression alludes to a line drawn at a stopping point of some kind. [Late 1700s]
See also: draw, line
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

draw the (or a) line at

set a limit of what you are willing to do or accept, beyond which you will not go.
1995 Kate Atkinson Behind the Scenes at the Museum She even manages to persuade Gillian not to cheat…although Gillian draws the line at not screaming when she loses.
See also: draw, line
Farlex Partner Idioms Dictionary © Farlex 2017

draw the line at, to

To set a specific limit, particularly on one’s behavior. This expression, heard in such contexts as “He drew the line at outright cheating,” comes from drawing some sort of boundary, but no one is quite certain as to what kind. Some speculate it comes from the early game of court tennis, in which the court had no specific dimensions and the players had to draw their own lines. Others believe it signified a line cut by a plow across a field to designate the property boundary. The term was used figuratively from the late eighteenth century on and was probably a cliché by the time W. S. Gilbert wrote, “I attach but little value to rank or wealth, but the line must be drawn somewhere” (H.M.S. Pinafore, Act I).
See also: draw, line, to
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer
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