四分戒本疏卷第一．第二．第三 2.19

2.19

The ninth precept: Defamation by fabricating grounds.
This precept requires fabricating a ground of seeing regarding a different matter, and taking the seeing of that matter to defame this person. Although the seeing corresponds [to an event], the matter does not correspond; this is called "fabricating grounds". If one claims to have heard what was seen, that is simply groundless, and is subsumed under the previous precept.
The intention of establishing the precept and the conditions for transgression are all the same as the previous precept, differing only in fabricating grounds. The text refers back to the holy injunction; therefore, it says: "Previously we heard that defaming with non-existent matters [incurs a penalty]; wishing to show that this is also limited, this statement was made."