A distinguishing feature of tadhyīl is that the addition constitutes a clause with a full predicative relation. Yet that clause is tied semantically to the statement it follows. Thus grammatical completeness and rhetorical dependence can coexist.
For instance: «انتهى الظلم؛ إن الظلم لا يدوم»
Oppression ended; oppression does not endure forever.
The second clause reinforces the particular report by a broader statement.