look before one leaps - Wiktionary, the free dictionary

look before one leaps (third-person singular simple present looks before one leaps, present participle looking before one leaps, simple past and past participle looked before one leaped or looked before one leapt)

1. (idiomatic) To think before taking action.

• haste makes waste
• marry in haste, repent at leisure

• he who hesitates is lost

• good things come to those who wait
• learn to walk before one can run