The Greek verb for "came forth from/out of" is exelthon.
It means "to proceed, to emanate (flow out, issue from as a source, as light issues from the sun),
to come out or go out of, to go forth."
See 1Co 14:36--"Did the word of God go forth from, originate with you?"
See Mt 2:6 (where different form, exeleusetai, is used)--"Out of thee will come forth a governor."
See Mt 15:18 (where a third form, like go, went and gone, is used, exerchontai)--"Out of the heart comes forth evil thoughts."
When "proceed, emanate, come out, go out, go forth" is used with ek, which means "out of, from (within)"
as in Jn 8:42, 16:28, it means "to proceed out from within, to emanate out from within, to come out from within, to go forth out from within,"
an emerging from within, an origin, and used by John in this sense, without exception, 336 times.
Jn 8:42 - "for out of (ek) God I went forth. . ."
See ekporeuomai in Mk 7:19 (goes out of--from within--the body),
in Rev 9:17 (out of--from within--their mouths come fire and smoke and sulfur)
in Rev 11:15 (fire comes out of--from within--their mouths).