Tradition
2 Timothy 2:2
And the things which thou hast heard of me by many witnesses, the same commend to faithful men, who shall be fit to teach others also.
Context of the passage
In his final letter, Paul instructs Timothy, a bishop he ordained, on preserving and transmitting the apostolic teaching to a new generation.
Catholic reading
This describes four generations of transmission (Paul → Timothy → faithful men → others), the pattern of apostolic succession by which doctrine is faithfully handed down through ordained teachers, not private interpretation alone.
Common objection
This simply describes normal discipleship and mentoring, not a formal teaching office with binding authority.
Response
Timothy's role as one who ordains others (1 Tim 5:22) and judges accusations against elders (1 Tim 5:19) shows this is structured ecclesial office, not informal mentoring, the seed of the episcopate that guards apostolic tradition.