John Chrysostom

"And there stood up one of them named Agabus, and signified by the spirit that there would be great dearth throughout the world, which also came to pass in the days of Claudius Caesar." "By the Spirit," it says: for, that they may not imagine that this was the reason why the famine came, namely, because Christianity was come in, because the demons were departed, the Holy Ghost foretells it: this, however, was nothing wonderful, for in fact Christ predicted it. …

Homily on Acts 25 ↗

Theophylact of Ohrid

"He foretold by the Spirit." Lest they think that the famine occurred because Christianity had appeared, the Holy Spirit also predicts this, because Christ too had predicted it. Not because "there will be a famine throughout all the world" as though it had to occur by virtue of a predetermination spoken from the beginning, but on account of the evils that were inflicted upon the holy apostles. And since these continued, the "great famine" also appears, foretelling to the Jews the calamities that were to come.

Commentary on Acts ↗

Bede

And one of them named Agabus, rising up, signified by the Spirit that there would be a great famine. Agabus can be interpreted as a messenger of tribulation, who, according to his name, both predicts the general famine here and later the bonds to the apostle Paul.

Commentary on Acts ↗