«أفصح الصبي في منطقه إذا بان وظهر كلامه»
A child becomes clear in speech when his words become plain and intelligible.
This usage does not necessarily describe sophisticated literary expression. It highlights the movement from obscure articulation toward understandable speech.
For example, speech that was once indistinct becomes sufficiently articulated for listeners to understand. This illustrates the lexical foundation of fasāḥah.