The Lord says that the preserved remnant shall...speak no lies,
and emphasizes this with the additional clause, Nor shall there be found in their mouth a deceitful tongue.
It could be that this repetition regarding the remnant’s truthful speech is meant to highlight the sharp contrast to the false prophets who filled their mouths with lies that drew the people into idolatry (Zephaniah 3:4; see also Zephaniah 1:4–6). The remnant, though descendants of Jacob the deceiver,1 will follow the pattern of the God who does not lie (Numbers 23:19; Psalm 89:35; Titus 1:2). They have as their Lord the one in whose mouth there was no deceit (Isaiah 53:9).2
13 those who are left in Israel; they shall do no injustice and speak no lies, nor shall there be found in their mouth a deceitful tongue. For they shall graze and lie down, and none shall make them afraid.”