night and day - 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 day and night. Continually, without stopping. This phrase is used either literally, as in The alarm is on night and day, or hyperbolically, as in We were working day and night on these drawings. Shakespeare put it by night and day in The Comedy of Errors (4:2): “Time comes stealing on by night and day.”