Stop IDOC processing and leave NAST-VSTAT as 0

Hello Experts

I need help understanding how I can stop the processing of a LAVA output if a certain condition is not met (I can manage that condition check in Userexit ZXTRKU02) and leave the output processing status as 0 (not processed, so it can be processed later).

So, for example I have a delivery which has a LAVA output attached. RSNAST00 runs, picks the delivery, executes the function associated to LAVA (IDOC_OUTPUT_DELVRY) and that function calls the userexit above. Inside the userexit there will be a condition check, that if it's not met, I would like to stop the IDOC creation process (not creating the idoc), but on the processing status in table NAST I would like to leave VSTAT = 0 (not processed), so on a later run of RSNAST00, the condition inside the userexit will be met and the outbound idoc will be created.

Thanks in advance.