Combine the honey, mustard, pineapple juice, lemon juice, garlic, and thyme in a medium bowl, whisking to blend well. Season with salt and pepper to taste.
Place the brisket in a resealable plastic bag. Add the honey mixture, seal, and refrigerate at least 1 hours or up to 24 hours.
When ready to cook, preheat the oven to 350°.
Transfer the brisket from the plastic bag to a nonstick roasting pan, discarding the plastic bag. Cover the pan with aluminum foil. Bake about 2 hours or until the brisket is very tender. About 15 minutes (or about 30 minutes if using a charcoal grill) before the brisket is ready, preheat and oil the grill.
Remove the brisket from the oven and transfer to the preheated grill. Grill, turning frequently, for about 12 minutes or until nicely charred. Remove from the grill and let rest a few minutes before slicing. Slice thinly against the grain and serve with barbeque sauce on the side.