«اِلْمَيَّهْ تِكَدِّبِ الْغَطَّاسْ»

Bragging about expertise costs nothing, but a real trial exposes it at once. A man who calls himself a skilled diver proves or disproves the claim only when he enters deep water, which serves as the test rather than a hazard to fear: either he swims back up, or his pretense sinks with him.

More broadly, the saying holds that performance, not self-description, establishes worth; its target is claimed ability, not truthfulness in general. Whoever makes a bold claim should expect a moment of testing that will honor the genuine and shame the pretender, so words should be measured against what one can actually do.

Apply it when someone claims a skill they have not yet demonstrated, or when an upcoming trial will decide who is genuinely capable. The saying points to the test itself, rather than argument, as what settles the claim.