Welcome jojorabbit!
if you bring someone into the truth you would get a "letter of recommendation"
I have heard the students who were baptized referred to as a "letter of recommendation" for the person who studied with them. Never heard about the benefit you describe ("That was to show you were a person who should make it through the end times into the new world.").
To find what was written on this (a quick search showed a few things), search on JW.org for II Corinthians 3:1.
Again, welcome.