Does the promise not to be anxious about how to speak or what to say apply to all who preach the gospel?
The promise not to be anxious about how to speak or what to say applies only to those dragged before a court of law. His promise that the words the apostles are to speak would be given to them in that hour
(Matthew 10:19; see Exodus 4:10–12, Jeremiah 1:6–10) was also a sign that they were justly resisting the authorities and that, when persecuted, grace will be given to them at the exact moment that it is needed. This complements the command not to be anxious, for faith is trust.
In Matthew 10:19–20, Jesus says that while the apostles will suffer for the sake of his name (see also Acts 9:4–5), all who are persecuted for his sake will never be deprived of his love and help (see Matthew 5:19–20,Matthew 5:29–31). Acts 4:8, Acts 6:10, and Acts 7:55–56 show how this prophecy is fulfilled in the apostles’ ministry.
No, not in the sense of the promise proclaimed by Jesus in Matthew 10:19, for there he speaks about being delivered over to a court of law rather than standing on a pulpit.1 To the apostles the promise that the words the apostles are to speak would be given to them in that hour
(Matthew 10:19) was not only a promise, but also a sign that they were justly resisting the authorities and that, when persecuted, grace will be given to them at the exact moment that it is needed. This complements the command not to be anxious, for faith is trust.2
Jesus here in Matthew 10:19–20 emphasizes that while the apostles will suffer for the sake of his name (see also Acts 9:4–5), all those who are persecuted for his sake, will never be deprived of his love, comfort, and strength (see Matthew 5:19–20, Matthew 5:29–31)3 As such the disciples ought not be anxious about what they should say or how they would have to articulate their message when they are interrogated. The words they are to speak would be given to them at that very hour (see also Exodus 4:10-12, Jeremiah 1:6-10). Later in Acts 4:8, 6:10, and 7:55-56 we also see how this prophecy is fulfilled in the ministry of the apostles (Bette, page 215).
19 Mais, quand on vous livrera, ne vous inquiétez ni de la manière dont vous parlerez ni de ce que vous direz: ce que vous aurez à dire vous sera donné à l'heure même;