Procrastination is the thief of time.
Verified
insighttimeSource: The Complaint: or, Night-Thoughts on Life, Death, and Immortality (Night I), Edward Young, 1742
Primary source solid: the line is from Night the First of Young's Night-Thoughts (1742) — 'Procrastination is the thief of time.' One of the most securely attributed lines in English proverbial verse; the surrounding line continues 'Year after year it steals, till all are fled.' Frequently quoted anonymously as a proverb, but Young is the author.