toe the line - Phrases/Idioms
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.
Also, toe the mark. Meet a standard, abide by the rules, as in The new director will make us toe the line, I'm sure, or At daycare Brian has to toe the mark, but at home his mother's quite lenient. This idiom refers to runners in a race placing their toes on the starting line and not moving until the starting signal. Its figurative use dates from the early 1800s.