The heart also of the rash shall understand knowledge, and the tongue of the stammerers shall be ready to speak plainly.
The heart also of the rash - the hasty: contrast "shall not make haste" (Isaiah 28:16); the reckless who will not take time to weigh religious truth aright. Or else, the well-instructed (Horsley).
The tongue of the stammerers shall be ready to speak plainly - those who speak confusedly on divine things shall receive a facility in speaking clearly concerning them (cf. Exodus 4:10-12; Jeremiah 1:6; Matthew 10:19-20; Luke 21:14-15). Or, those drunken scorners who in stammering style imitated Isaiah's warnings, to mock them (Maurer). (Isaiah 28:7-11; Isaiah 28:13-14; Isaiah 28:22; Isaiah 29:20.) But the "scorners" in Isaiah 28:17-22 were to be destroyed, not converted. Therefore "the stammerers" are rather the servants of God who now speak but stammeringly of divine things, as compared with the spiritual utterance which the saints shall hereafter have in Messiah's manifested kingdom. For "speak plainly," translate, 'speak uprightly' (agreeably to the divine law); not as English version, referring to the distinctness of articulation, plainly. The Hebrew, tsaachowt (H6703), is literally, white: so candid things, candidly, sincerely, uprightly.