Семь раз отме́рь, оди́н отре́жь.
~ Russian Proverb
Transliteration: Sem’ raz otmer’, odin otrezh.
Literal translation: Measure seven times, cut once.
English equivalent: Measure twice and cut once.
If you’re about to do something that you can’t change, you’d better make sure you do it right. So check your work, then double check it, and only then should you take action.