Bennett, who has seen a specialist and continues to be monitored, has not practiced this week because of concussion-related symptoms after last week's loss to the New York Giants. He complained of headaches, fogginess and that "his eyes were hurting," coach Wade Phillips said Thursday.
In his second season, Bennett is sixth on the team with 15 catches for 159 yards.
Hamlin will be missing his fourth consecutive game with a high ankle sprain.
On Friday, Phillips ruled out moving tight end Scott Chandler from the practice squad to the active roster.
With Bennett out, the Cowboys could activate linebacker Jason Williams on Sunday. Williams, a third-round pick, has played in only two games this season.
Information from The Associated Press contributed to this story.