Irenaeus
Against Heresies 3.10.5 · Mark 16:19
“He was received up into heaven”
Short excerpt from the linked English translation
What this supports
Irenaeus names Mark and quotes a verse from the longer ending. This is early evidence that the ending was known before the KJB.
What still needs care
The work survives through later copies. This is not an original second-century manuscript of Mark, and it does not remove the need to examine copies with other endings.
Cyprian
On the Unity of the Church 6 · 1 John 5:7–8
“And these three are one.”
Short excerpt from the linked English translation
What this supports
Cyprian uses this phrase in a discussion of Father, Son and Holy Spirit. KJB defenders regard this as important early support for the heavenly-witness reading.
What still needs care
Whether he read the longer wording in his Bible or interpreted the shorter wording in a Trinitarian way remains disputed. A verse number added by a later editor does not settle that question.
Jerome
Letter 27 to Marcella, sections 1 and 3 · Latin and Greek Gospel copies
“the Latin manuscripts of the Scriptures are proved to be faulty”
Short excerpt from the linked English translation
What this supports
Jerome says he compared differing Latin copies with Greek. His letter records an early argument about correcting a translation by consulting its source language.
What still needs care
This is Jerome’s explanation of his work, not proof that every decision he made was correct. It does not establish any single later English translation by itself.
Victor of Vita’s record
History of the Vandal Persecution 2.11, section 82 · 1 John 5:7–8
“There are three who bear witness in heaven”
Short excerpt from the linked English translation
What this supports
The Latin statement recorded in Victor’s work attributes the heavenly-witness wording to John. It documents use of the reading long before 1611.
What still needs care
A shared statement is not an inspection of every bishop’s personal Bible. The linked modern article reproduces the Latin and an English translation; it is not a photograph of the fifth-century original.