Hi Saber,
1. First create 2 sets in GS01. One for vendors (BSEG-LIFNR) and other one for users (SYST-UNAME). And maintain the vendors list and users list, which they will authorize to post.
2. Then after create a validation at line item level in GGB0 as shown below:
Prerequisite: BSEG-LIFNR IN XXXX (Vendors set name)
Check : SYST-UNAME IN XXXX (Users set name)
Message: Error message
3. After that activate the validation in OB28 for the co.code.
Regards,
Mukthar
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