no vendas la piel del oso antes de cazarlo

1.
SpainLatin Americaneutralproverbial
- Literally: do not sell the bear's skin before hunting the bear.
2.
SpainLatin AmericaOther Spanish-speaking regionsneutralproverbial
- Figuratively: do not assume you will obtain or profit from something before it is secured; do not count on success prematurely.

Examples:

ES: Como decimos en Texas, señorita, "no vendas la piel del oso antes de cazarlo".
EN: We got a sayin' down in Texas, ma'am, about counting' your chickens before they're hatched.
ES: Hay muchas bofetadas antes de vender la piel, Ray. He tenido que traducirlo de una forma un tanto libre. El original dice "there's many a slap twixt a cup and a lap", del refrán "there's many a slip twixt the cup and the lip", que vendría ser un "no vendas la piel del oso antes de cazarlo".
EN: There's many a slap twixt a cup and a lap, Ray.
ES: Oye, no vendas la piel del oso antes de cazarlo.
EN: Hey, don't count your chickens, buster.