John Calvin Commentary Acts 10:22

"And they said, Cornelius a centurion, a righteous man and one that feareth God, and well reported of by all the nation of the Jews, was warned [of God] by a holy angel to send for thee into his house, and to hear words from thee." — Acts 10:22 (ASV)

Cornelius, a just man. Cornelius’s servants commend their master not ambitiously, or so that they might flatter him, but so that Peter might abhor his company less. And for this reason, they say that he was approved by the Jews, so that Peter might know that he was not estranged from true and sincere godliness.

For even those who were superstitious, though they served idols, boasted that they were worshippers of God. But Cornelius could not have had the Jews, who retained the worship of the true God alone, as witnesses of his godliness, unless he had professed that he worshipped the God of Abraham with them.

Furthermore, as this was a rare example, it ought to have moved Peter considerably. Although they rely most of all on this argument—that this entire matter is governed by God’s command—to persuade him concerning their mission, it is as if they were saying that he is called not so much by a mortal man as by God, who had commanded this through His angel.