Coach Chan Gailey calls the decision to rest Merriman a precaution. He adds Merriman would have likely played if this were a regular-season game.
Merriman has missed the past two days since hurting his knee during a pass-rushing drill. He had two sacks in Buffalo's 10-3 preseason-opening loss at Chicago last weekend.
Receiver Roscoe Parrish will also sit out after missing a week of practice due to a leg injury.
The Bills wrapped up three weeks of training camp in suburban Rochester on Thursday and will resume practicing at their headquarters in Orchard Park next week.