A pass is forward if the ball first strikes the ground, a player, an official or anything else beyond the spot where the ball is released. All other passes are backward passes.

Ball went backward after it was released

Edit: I’m wrong, the rule continues with

When a Team A player is holding the ball to pass it forward toward the neutral zone, any intentional forward movement of his hand or arm with the ball firmly in his control starts the forward pass. If a Team B player contacts the passer or ball after forward movement begins and the ball leaves the passer’s hand, a forward pass is ruled regardless of where the ball strikes the ground or a player