"It's been an emotional week for [Stewart]," Brett Frood, executive vice president of
Stewart opted not to race at Michigan this weekend; he also missed the prior NASCAR Sprint Cup Series race at Watkins Glen, N.Y.
Stewart "made the decision he's not ready to get in the race car and will take it week by week," Frood said. "It will be up to Tony when he's ready to get back in the car.
"It was a tragic accident and he's dealing with quite a bit of grief," Frood said, adding that Stewart "is surrounded right now by his closest friends and family. His location is of a private nature."
Frood also said "right now the focus of everyone should be on the [Ward] family that's grieving."
During a non-NASCAR, sprint-car race at a small dirt track in upstate New York on Saturday, Ward emerged from his wrecked car, stood on the track and, while apparently gesturing toward Stewart, was hit by Stewart's car.
An amateur video of the incident available on the Internet has sparked widespread public debate about who might have been at fault in Ward's death.
Stewart has not been charged with any wrongdoing but an investigation by local law enforcement authorities is continuing.
"We're going to respect that process and the people involved in that investigation," Stewart-Haas spokesman Mike Arning said.