“But when they deliver you up, do not be anxious how or what you shall speak, for it will be given you in that hour what you shall speak, for it is not you who speak, but the Spirit of your Father who speaks in you.”
And when these dreadful experiences did happen they were not to be afraid and anxious. Nor should they be afraid as to what defence they should put up. Rather they are to recognise that in that very hour God will give them the words to speak (‘it will be given you' - the divine passive). For they will not speak on their own. It is the Holy Spirit Who will speak through them. It should be noted how well these words suit these humble, inexperienced men going out on a task that must have appeared so huge. Then the thought of those courts would be terrifying. The words might not be quite so important when they were more experienced (although they would still important, even if in a different way). Luke cites similar words, but he never specifically suggests that they were fulfilled in Acts, even though Paul did appear before one king and a number of governors. He too could thus have seen them as at least partially fulfilled on these first ‘missionary' journeys.
‘The Spirit of your Father.' This is the only place in the New Testament where this phrase is found, but it was a reminder to them that all the time that they were on their journeys their Father would be watching over them, providing for them both bread and clothing (Matthew 6:30; Matthew 6:32), and now the very words that they should speak when put on trial. As they stood alone before these governors and kings, they would not be alone. Their Father would be with them through His Spirit. Where other would be tongue-tied, their tongues will be freed with the wisdom of their Father.
Note how in the chiasmus this verse parallels that which speaks of their testimony before the highest authorities and before the Gentiles. Here above all they will need the Spirit of their Father to guide their words.