Horford (rest) is out for Friday's game versus the Magic due to rest purposes, Chris Forsberg of NBC Sports Boston reports.
Horford hasn't suffered any injury but will sit out the second leg of Boston's back-to-back against Orlando. With Luke Kornet (groin) out and Kristaps Porzingis (calf) doubtful, Neemias Queta will likely be the Celtics' only available big man. Horford should be able to suit up for Sunday's rematch with the Magic.