The Greek that is often translated as «testify» in English has the option of terms in Luang with different shades of meaning.

For Acts 10:42, nala linniohora-matniohora («give ear-eyes about»). «This term is used when the witness actually saw the event and testifies truthfully about what he has seen.»

For Acts 10:43 and 20:24, raltiernohora («talk-about»). «The focus of this term is on the talking, only without reference to the truth of the testimony. It may be used of a false witness.»

Source: Kathy Taber in Notes on Translation 1/1999, p. 9-16.

See also testimony.