A.T. Robertson Commentary Acts 18:6

"And when they opposed themselves and blasphemed, he shook out his raiment and said unto them, Your blood [be] upon your own heads; I am clean: from henceforth I will go unto the Gentiles." — Acts 18:6 (ASV)

When they opposed themselves (αντιτασσομενων αυτων). Genitive absolute with present middle (direct middle again) of αντιτασσω, old verb to range in battle array (τασσω) face to face with or against (αντ). In the N.T. only here and Ro 13:2; James 4:6; 1 Peter 5:5. Paul's fresh activity roused the rabbis as at Antioch in Pisidia and at Thessalonica in concerted opposition and railing (blasphemy).

He shook out his raiment (εκτιναξαμενος τα ιματια). First aorist middle of εκτινασσω, old verb, in the N.T. only here as in 13:51 (middle) and Mr 6:11; Matthew 10:15 where active voice occurs of shaking out dust also. Vivid and dramatic picture here like that in Ne 5:13, "undoubtedly a very exasperating gesture" (Ramsay), but Paul was deeply stirred.

Your blood be upon your own heads (Το αιμα υμων επ την κεφαλην υμων). As in Eze 3:18f., 33:4,8f.; 2 Samuel 1:16. Not as a curse, but "a solemn disclaimer of responsibility" by Paul (Page) as in Ac 20:26. The Jews used this very phrase in assuming responsibility for the blood of Jesus (Matthew 27:25). Cf. Matthew 23:35.

I am clean (καθαρος εγω). Pure from your blood. Repeats the claim made in previous sentence. Paul had done his duty.

From henceforth (απο του νυν). Turning point reached in Corinth. He will devote himself to the Gentiles, though Jews will be converted there also. Elsewhere as in Ephesus (19:1-10) and in Rome (Acts 28:23–28) Paul will preach also to Jews.