The indication of the (kind of) evidence for a statement is known as evidentiality in linguistics.
The wikipedia article referenced above gives the example of Eastern Pomo, in which a verb takes one of 4 evidential suffixes, corresponding to the type of evidence: nonvisual sensory, inferential, hearsay, or direct knowledge (probably visual).
The indication of the (kind of) evidence for a statement is known as evidentiality in linguistics.
The wikipedia article referenced above gives the example of Eastern Pomo, in which a verb takes one of 4 evidential suffixes, corresponding to the type of evidence: nonvisual sensory, inferential, hearsay, or direct knowledge (probably visual).