For I will give you a mouth and wisdom, which all your adversaries shall not be able to gainsay nor resist.

for I will give you a mouth and wisdom, which all your adversaries shall not be able to withstand or to gainsay.

For I will give you a mouth and wisdom, which all your adversaries shall not be able to resist and gainsay.

for I will give you a mouth and wisdom which all your opposers shall not be able to reply to or resist.

for I will give to you a mouth and wisdom that all your opposers shall not be able to refute or resist.

for I will give you utterance and wisdom which none of your opponents will be able to withstand or reply to.

For I will give you words and wisdom, so that not one of those who are against you will be able to get the better of you, or to put you in the wrong.

For I will give to you a mouth and wisdom, which all your adversaries will not be able to resist or contradict.

for I will myself give you words, and a wisdom which all your opponents together will be unable to resist or defy.

A mouth - Eloquence, ability to speak as the case may demand. Compare Exodus 4:11.
Gainsay - Speak against. They will not be able to "reply" to it, or to "resist" the force of what you shall say.

I will give you a mouth and wisdom - Στομα, a mouth, must appear plain to every person to be used here for a ready utterance, or eloquence in speaking. They shall have an abundance of wisdom to know what to say; and they shall have an irresistible eloquence to say what they ought.

For I will give you a mouth,.... A faculty of speaking, a freedom of expression, a door of utterance, a good degree of elocution, to speak properly, pertinently and freely to any point:
and wisdom; to answer with great propriety, and in the most prudent manner, to any difficult and ensnaring question; and to furnish with such knowledge of the Gospel, and with such gifts and abilities to preach and defend it, that they should be able to give a clear and distinct account of it, and prove every point in it, by the most strong and convincing arguments, and vindicate it against all objections:
which all your adversaries shall not be able to gainsay or resist. This was remarkably fulfilled in Peter, and John, and in Stephen, Acts 4:13. The first word, "gainsay", is left out in the Syriac and Persic versions.