Zion Williamson needs to IGNORE Scottie Pippen's advice and NOT sit out the rest of the college basketball season because it could hurt his development ... so says Kenny Smith.
"When you play, you get an opportunity to hone your craft," Smith tells TMZ Sports ... "Iron sharpens iron."
Pippen sees it MUCH differently -- claiming the Duke superstar is the obvious #1 overall pick in the NBA Draft and he needs to sit out to avoid risking serious injury.
But, Smith says sitting will essentially stunt his growth -- because the constant competition with top college talent will make him more prepared for the jump to the NBA.
Check out the clip ... Kenny sends a personal message to Zion to keep playing ... and throws a little jab about the big UNC/Duke rivalry.
P.S. -- Yes, a Tar Heels legend is giving a Blue Devil advice. Last time we checked, hell hasn't frozen over ... yet.