Where did the rich young ruler hear of eternal life? Something prompted the young ruler in Matthew 19:16 to ask Jesus what he must do to inherit eternal life. (Word search for "eternal life" and "everlasting life" )

The phrase "everlasting life" appears once in the OT, in Daniel 12:2. Jesus' usage in the gospels is brief. What did the ruler hear that made him rush to Jesus to ask for it? Are there any clues I missed that give us a fuller picture? Are there Christian writings that have addressed this point?
The Pharisees were the dominant religious sect of Judaism in Jesus's time. They taught strict adherence to the Law and all of the other laws added to it. They also taught the resurrection of the dead. In their contemporary writings, the Pharisees talk about eternal hell and they used very specific terms we know mean eternal hell because they explain it at length. They also believed in eternal life as an alternative if one followed the laws to a T.

The rich young ruler said he'd kept the Commandments since he was a boy, so it's possible he held Phrisetical beliefs. He would have also heard teachings about eternal life from the Pharisees.

It's important to note that Jesus did not use the same terms to describe hell that the Pharisees used. Jesus used words that normally mean age-bound correction. But due to doctrinal beliefs shifting in the 5th Century A.D., the Latins began translating His words as eternal judgment and eternal punishment. Due to the difference in terms that Jesus used, it's possible the rich young ruler was drawn to Jesus' more loving teachings of God rather than the harsh Pharisetival teachings he'd grown up seriously adhering to. The Greek Church Fathers taught that hell was temporary and everyone there would eventually be purified and go to heaven. They were the first Church Fathers and spoke the New Testament's Koine Greek as their native language and therefore understood it perfectly well.

Also, in the Old Testament, eternal life doesn't appear, just as eternal torment doesn't appear either, not when translated properly. The Ancient Hebrews of Abraham's day were nomads and their Paleo-Hebrew language (Pheonecian) was built around the way they thought and lived--with nomadic terms.

"Olam/Owlam" is their word we translate to mean eternal. However, "olam" doesn't mean eternal. It literally means "over the horizon," which is their way of saying "future," because they didn't know what was over the horizon until they got there. They had another saying that meant the distant future (I forget the exact phrase), which literally means "over the horizon and back." In their culture, they didn't speculate on things they didn't know for certain. So they simply described the afterlife as the unseen or as the future or distant future.

Life was described the same way, as "future" life or "distant future" life. Our translators simply translated their mainstream doctrinal and cultural beliefs into the texts, which is nearly impossible not to do if you understand how translation must be done and how much has to be guessed at due to cultural differences and unknowns such as their exact beliefs back then. Translation isn't nearly as simple as "Casa" means "home" in Spanish. It's extremely difficult and pretty much impossible to get a 100% accurate translation.

Despite what I just said about the word eternal, that doesn't mean eternal life isn't stated in the Bible. When the Koine Greek word aion/aionios/aionion (age or age-bound) is paired with something we know to be eternal (like God), then we translate aionios as "eternal." The problem, though, is that we don't know for certain if judgment or punishment is eternal, yet we translate aionios to mean "eternal." Since the Church Fathers use the term aionios punishment/judgment just like Jesus but in the same sentence say that the person being judged/punished is purified by it and then goes to heaven, this likely proves that the term doesn't actually mean "eternal" when paired with judgment/punishment.

Furthermore, the Koine Greek words Jesus &amp; Paul used for punishment and judgment are corrective terms rather than vengeful terms. Corrective implies an end purpose of purification rather than annihilation or eternal torment.

In other words, the word used to describe eternal is a very controversial term, but when used in relation to life, we're pretty sure it means eternal life, but in the Old Testament, we don't know for certain that the idea of eternal life, as we conceptualize it, is ever used. We do know that the general beliefs and ideas from the Old Testament are being conveyed in the New Testament by Jesus and the other writers, though, because they quote the Old Testament so frequently.

I hope that wasn't too in-depth or too widely focused to answer your question to your liking.