Jude 3 says nothing whatsoever concerning sola scriptura. There are better verses that Protestants use to support the notion, but there is is no point in providing any amunition for an errant notion. Have your friend explain why we are told that we must hold to traditions whether they are oral or written. Give them these verses to study and reflect on.
So then, brothers and sisters, stand firm and hold fast to the traditions that you were taught by us, either by word of mouth or by our letter.
2 Tim 2:2
and what you have heard from me through many witnesses entrust to faithful people who will be able to teach others as well.
1 Cor 11:2
I commend you because you remember me in everything and maintain the traditions just as I handed them on to you.
1 Thess 2:13
We also constantly give thanks to God for this, that when you received the word of God that you heard from us, you accepted it not as a human word but as what it really is, God’s word, which is also at work in you believers.
They devoted themselves to the apostles’ teaching and fellowship, to the breaking of bread and the prayers.
Also challenge them with this question: “For the Christian, what is the pillar and bulwark of the truth?” When they answer that it is scripture/the bible, show them 1 Tim 3:15 which says:
" if I am delayed, you may know how one ought to behave in the household of God, which is the church of the living God, the pillar and bulwark of the truth."
I hope this helps