Exodus 4:7

⁷ And he said, Put thy hand into thy bosom again. And he Put his hand into his bosom again, and drew it out of his bosom, and behold, it was turned again as his other flesh.

Dumb

To be dumb, or unable to speak, as in Exodus 4:11 and Isaiah 35:6, signifies people who cannot confess the Lord because they are ignorant of the truth. (Arcana Coelestia 6988, Apocalypse Explained 455)

In Mark 9:25, this signifies one who does not want to perceive and understand truth. (Apocalypse Explained 556)