«يصدق الخبر بمطابقته للواقع، ويكذب بعدم مطابقته له»
A report is true if it corresponds to reality and false if it does not.
For “عَلِيٌّ مُقِيمٌ” (“Ali is resident”), the issue is whether Ali is in fact resident. If so, the report is true; otherwise it is false. Reality means the actual state of affairs to which the assertion refers, whether it is an external event or some other relevant fact.
The speaker's confidence, the persuasive manner of delivery and the listener's impression may matter rhetorically, but correspondence between claim and fact is the criterion of truth here.