Long time therefore - It seems probable that there were here no forcible or public measures to expel them, as there had been at Antioch Acts 13:50, and they therefore regarded it as their duty to remain. God granted them here also great success, which was the main reason for their continuing a long time. Persecution and opposition may be attended often with signal success to the gospel.
Spake boldly in the Lord - In the cause of the Lord Jesus, or in his name and by his authority. Perhaps, also, the expression includes the idea of their trusting in the Lord.
Which gave testimony - Bore witness to the truth of their message by working miracles, etc. Compare Mark 16:20. This was evidently the Lord Jesus to whom reference is here made, and it shows that he was still, though bodily absent from them, clothed with power, and still displayed that power in the advancement of his cause. The conversion of sinners accomplished by him is always a testimony as decided as it is cheering to the labors and messages of his servants.
Unto the word of his grace - His gracious word, or message.
And granted signs ... - Miracles. See the notes on Acts 2:22.