A proverb to denote the importance of talking and acting in showing your abilities

As far as the negative side of your proverb goes, there is a popular quote that in slightly different forms has been attributed to various sources, from Abraham Lincoln, to Mark Twain, to the Bible:

Better to remain silent and be thought a fool than to speak and to remove all doubt.
Abraham Lincoln

I've heard this one on multiple occasions:

Sometimes you need to toot your own horn.

However, that wording is usually meant to say that you need to promote your own strengths, but not necessarily show your weaknesses.

Although some dictionaries define toot your own horn as a way of boasting, I've heard it used in contexts where someone is not boasting, but perhaps should be letting someone know a little more about the behind-the-scenes work they have been doing; for example:

Ed: You worked hard on that project! I'm surprised you didn't get the promotion.
Ted: Maybe so, but I don't think the boss knows much about what goes on around here after 5 o'clock.
Ed: Well, Ted, sometimes you need to toot your own horn.

If you want to emphasize that you are sharing both stengths and weaknesses, you could say:

I'm going to lay my cards on the table.

which is used as a metaphor to describe being totally candid about an issue.

I don't think either of these match the Persian proverb completely, but they both have a bit of overlap.

The nearest English equivalent is probably ‘Don’t hide your light under a bushel.’ This is adapted from a story in the Bible, and it means that you shouldn't hide your talents. Bushel is an obsolete word for a bowl.

Here’s the full text, from Luke 11:33-36 in the King James Bible:

No man, when he hath lighted a candle, putteth it in a secret place, neither under a bushel, but on a candlestick, that they which come in may see the light. 34 The light of the body is the eye: therefore when thine eye is single, thy whole body also is full of light; but when thine eye is evil, thy body also is full of darkness. 35 Take heed therefore that the light which is in thee be not darkness. 36 If thy whole body therefore be full of light, having no part dark, the whole shall be full of light, as when the bright shining of a candle doth give thee light.

I think the nearest common phrase is:

the proof of the pudding is in the eating.

This means you do not know the quality of something until you try it for that particular purpose. Literally it refers to eating, and has the implied meaning that you can't judge how delicious or satisfying a dish is from just its appearance. It can can be used as an invitation to someone to demonstrate their abilities.

Edit:

• If you want to be heard, speak up.
  If you want to be seen, stand up.
  If you want to be appreciated,
  Just shut up.

(Source 1 Source 2.)

Original post:

• Tell me a story and I will tell you who you are.

  (Tell me a story and I'll tell you who you are.) I have heard it used, more than once. I don't see it in my refence books, but to prove that it is used:

  "(Küfner, A.C.P., Back, M.D., Nestler, S., & Egloff, B. (2010). Tell me a story and I will tell you who you are! Lens model analyses of personality and creative writing. Journal of Research in Personality, 44.)"

  I have a hunch it's been created by analogy from this:
  "You are what you Eat - Mann ist was Mann isst, man is what man eats. The saying is sometimes attributed to the French gastronome Anthelme Brillat-Savarin who wrote in his Physiologie du Goût(1825): Dis-moi ce que tu manges, je te dirai ce que tu es. Tell me what you eat, and I will tell you what you are." (The Concise Oxford Dictionary of Proverbs, 3rd ed, 2003)

• A man is known by his words.

  "(Lauhakangas, O. A Man is known by his Words: The Functions of Proverbs in Social Interaction. Helsinki: Suomalaisen Kirjallisuuden Seura, 2004.)"