einmal ist keinmal

Etymology
lit. 'once is never'.

Proverb

 * 1) Once doesn’t count; one swallow does not a summer make
 * 2) One slip is allowed; everyone deserves a second chance
 * 3) One time won’t hurt; just try it
 * 1) One time won’t hurt; just try it
 * 1) One time won’t hurt; just try it