Luke 21:15

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 Acts 4:14 ) ( 6:10 ) . The first word, "gainsay", is left out in the Syriac and Persic versions.