Not offside
The provision as it is printed, and everything on Ruleside that turns on it.
An attacker (C) is in an offside position, not interfering with an opponent, when a team-mate (A) passes the ball to player (B1) in an onside position who runs towards the opponents' goal and passes the ball (B2) to team-mate (C). Attacker (C) was in an onside position when the ball was passed, so cannot be penalised.
Worked by IFAB itself 1
One of the positions the Laws answer by name rather than by rule, drawn.
The Laws of the Game are published by The IFAB and quoted here for the purpose of explaining the decisions on this site. Ruleside is not affiliated with The IFAB or FIFA. Every clause of Practical guidelines for match officials that Ruleside cites.