Day and night he toiled tirelessly without the slightest slackening.
Tips
usage
Common in 松懈 ('to slacken, let one's guard down') and 懈怠 ('to slack off, be negligent'). The heart radical signals it describes an inner attitude of effort, not physical looseness.
The left-side heart radical (the upright form of 心) marks this as a state of mind: it places 懈 among feeling-and-attitude words, here the slackening of willpower.
