[soadyp]

Under FIBA: Ball can be passed between team mates behind the line after a Field Goal.

Rule:
17.2.7. Following a successful field goal or a successful last or only free throw:
• Any player of the non-scoring team shall take the throw-in at any place behind that team’s endline. This is also applicable after an official hands or places the ball at the disposal of the player taking the throw-in after a time-out or after any interruption of the game following a successful field goal or a successful last or only free throw.
• The player taking the throw-in may move laterally and/or backwards and the ball may be passed between team-mates behind the endline, but the 5 second count starts when the ball is at the disposal of the first player out-of-bounds.

There is also matching official interpretation that covers leaving the ball on the floor.

Official Interpretations 2014: (current at time of post)
17-7 Example: After a team A successful field goal or a successful last or only free throw a timeout is granted to team B. Following the time-out B1 receives the ball from the official for a throw-in at the endline. B1
(a) places the ball on the floor after which the ball is taken by B2.
(b) hands the ball to B2, who is also standing behind the endline.
Interpretation: Legal play. The only restriction for team B to handle the ball on the throw-in is they must pass the ball into the playing court within 5 seconds.