Take your hands off his cock for a few seconds, and then go back to the long slow strokes from the base of his penis all the way up over the top of his cockhead. Don’t be surprised if he groans with pleasure at the increase in friction. As always, keep stroking while you speak to him.
Say: “O, does it feel nice when I stop and then start again? I’m learning so much about what gives your cock pleasure. That’s going to make it so much easier for me to bring you closer and closer to cumming without going over the edge.”