The best and earliest source would probably be Papias, AD 130, about 50 years before Irenaeus.
Here is a quote from Ed Stevens on this subject (underlining mine):
"
• Notice what Eusebius and Irenaeus (late second century) said about Papias in relation to the apostle
John and his martyrdom [Source: Eusebius (ca. 260– 340), Chronicle. Text: A. Schöne, Eusebi
Chronicorum canonum quae supersunt, vol. 2 (Berlin: Weidemann, 1866), 162.] :
Pap. 5:5 Papias says in his second book that John the Theologian and James his brother were
killed by Jews.
Pap. 6:3 For Papias, the bishop of Hierapolis, who had seen him with his own eyes, claims in the
second book of the Sayings of the Lord that John was killed by Jews, thus clearly fulfilling,
together with his brother, Christ’s prophecy concerning them and their own confession and
agreement about this.
Pap. 6:4 For when the Lord said to them, “Are you able to drink the cup that I drink?” and they
eagerly assented and agreed, he said: “You will drink my cup and will be baptized with the
baptism with which I am baptized.”
Pap. 6:5 And this is to be expected, for it is impossible for God to lie.
Pap. 6:6 [Eusebius said later] Moreover the encyclopedic Origen also affirms in his interpretation of
the Gospel according to Matthew that John was martyred, indicating that he had learned this
from the successors of the apostles [i.e., possibly referring to Papias].
• Papias claimed that John was killed by the Jews, evidently at a time when they still had the ability
and opportunity to do so. This would point to the Neronic persecution (AD 64), until it was cut short
by the outbreak of the Jewish revolt (AD 66). It would not have been easy for them to do much
against Christians after the war began, and especially not after the war ended.
• The Jews had no political or judicial power to kill anyone after 70. It clearly points to a time before 70
when the Jews would have had the authority, opportunity, and means by which to do it. The
Neronic persecution fits that description well, since that is when the Jews were in their most
powerful position against the Christians."
This is from pages 56-57 of his free PDF book, Final Decade Before the End.
BTW I heartily recommend this PDF. It is easy to find on the Internet. If not I will gladly send anyone a copy. A lot of research went into this. John, you would do well to take a look at this as well. It might help you to much better understand, not only this particular topic, but Full Preterism, what it is and is not.