The point is whether it is a metaphorical or literal proposition that infants "speak lies."
Since infants don't speak, then they don't speak lies.
Speaking = verbalizing.
It's a metaphor, OP. Probably we'll disagree and this isn't worth carrying forward for me...the capabilities of infants are just too obvious, so the intent of the verse is too obvious.
No, "speaking" does not always equal "verbalizing". The great majority of all human communication is non-verbal.
Beyond which, if it's a "metaphor", then what is the meaning of the metaphor but simply this:
What other "metaphorical" meaning can you deliberately and artificially shoe-horn into the verse, without destroying the teaching thereof about infants?
Remember, the Verse is about the morality of Infants. Does it "metaphorically" describe the morality of Infants as SINFUL, or INNOCENT? Well, which is it, Xzins?
It's a simple question, and I want a straight answer.