Had played a few pots vs each other to this point. Blinds are 250-500/50 he is eff stack with 21k on button, I am in SB (BB has 8k fwiw) holding 9s9d. Jon opens to 1200, I reraise to 3500 he calls. Flop comes Kd6h4h (8k pot) i cbet for 3500 and he shoves 17.5k total. Would enjoy hearing thoughts on the hand pre and post flop, would you cbet or check, do you call the shove or fold and why?