Whats the call?

[march_madness]

I had a game situation last week that I need help on.

Player A1 drives to the basket for an attempted shot, While in the air Player A1 changes his mind and decide to pass the ball off to A2. A2 did not expected the pass and the ball was about to go out of bound. A1 decide to go after his pass and retrieve the ball from going out of bound.

Another word A1 pass the ball but no one touches it and A1 went after to retrieve the ball or tap it to his teammate is that legal or not?

I cannot find the ruling anywhere in the rule book.
Can someone please tell me what section of the rule is this ruling is located in?