A.T. Robertson Commentary Acts 9:15

"But the Lord said unto him, Go thy way: for he is a chosen vessel unto me, to bear my name before the Gentiles and kings, and the children of Israel:" — Acts 9:15 (ASV)

A chosen vessel (σκευος εκλογης). A vessel of choice or selection. The genitive of quality is common in the Hebrew, as in the vernacular Koine. Jesus chose Saul before Saul chose Jesus. He felt of himself that he was an earthen vessel (2 Corinthians 4:7) unworthy of so great a treasure. It was a great message that Ananias had to bear to Saul. He told it in his own way (9:17; 22:14f.) and in 26:16f. Paul blends the message of Jesus to Ananias with that to him as one.

Before the Gentiles (ενωπιον των εθνων). This was the chief element in the call of Saul. He was to be an apostle to the Gentiles (Ephesians 3:6–12).