Acts 13:45

But when the Jews saw the multitudes, they were filled with envy, and spake against those things which were spoken by Paul, contradicting and blaspheming.

When the Jews saw the multitudes gathered to hear Paul and Barnabas, they were filled with envy and set themselves against the preaching by contradicting what was spoken and speaking blasphemously against it.
This took place at Antioch in Pisidia on the second Sabbath, when almost the whole city came together to hear Jesus preached as Saviour and promised Messiah, with great numbers of Gentiles mingling with the Jews in the congregation, although on the first Sabbath the Jews had listened with intense interest.
In this their reaction repeated that of the priests and rulers in the days of Christ when they saw multitudes assembled to hear new doctrine.
Their old bigotry and prejudice were aroused because they could not endure that Gentiles should enjoy religious privileges on an equality with themselves.
They clung tenaciously to the idea that the blessing of God was reserved exclusively for themselves, which had ever been their great sin, the same exclusiveness Christ had rebuked.
Learning that the Messiah preached was to be a light to the Gentiles as well as the glory of Israel excited them to anger and a frenzy of indignation and rage.
Anger distorted the apostles' words in their minds and left them unfitted to fairly weigh the evidence presented, driving them to insulting language.
This opposition led the apostles to turn without hesitation to the Gentiles.
As an instance of envy, contradiction and blasphemy set against the preaching of truth, the verse belongs to the light of the thirteenth chapter of Acts showing that the Lord will not encourage false theories and a low standard.
It calls God's people to seek the Lord most earnestly, humble their hearts before God, and receive the refining, enlightening and sanctifying work of the Holy Spirit as a refiner and purifier of silver so that dross is removed and God's glory is revealed.
It requires a higher moral standard in printing offices, sanitariums and every line of work, with decided change, reformation and conversion of the entire church.
It warns that it is too late to trifle with truth, that those who see no need of this work and continue in unconverted principles will surely reap the results, and that failure to recognize the working of the Holy Spirit forfeits wonderful victories.