What prophecy was about Timothy?

Paul refers to a prophecy about Timothy > **1 Tim 1:18-19 ESV** Timothy, my son, I am giving you this command in keeping with the **prophecies once made about you**, so that by recalling them you may fight the battle well, holding on to faith and a good conscience, which some have rejected and so have suffered shipwreck with regard to the faith. Which prophecy is he talking about?