Where is the “Tradition”, ask my Muslims friend? Not what is Tradition. I’ve shared the Catechism 78 and other part of the CCC, as well:
"78 This living transmission, accomplished in the Holy Spirit, is called Tradition, since it is distinct from Sacred Scripture, though closely connected to it. Through Tradition, "the Church, in her doctrine, life and worship, perpetuates and transmits to every generation all that she herself is, all that she believes."37 "The sayings of the holy Fathers are a witness to the life-giving presence of this Tradition, showing how its riches are poured out in the practice and life of the Church, in her belief and her prayer.“38”
I also read from Catholic.com that if there is a canon of scripture, the Church also as a “canon of Tradition”:
The indefectible Church
The task is to determine what constitutes authentic tradition. How can we know which traditions are apostolic and which are merely human? The answer is the same as how we know which scriptures are apostolic and which are merely human—by listening to the magisterium or teaching authority of Christ’s Church. Without the Catholic Church’s teaching authority, we would not know with certainty which purported books of Scripture are authentic. If the Church revealed to us the canon of Scripture, it can also reveal to us the “canon of Tradition” by establishing which traditions have been passed down from the apostles. After all, Christ promised that the gates of hell would not prevail against the Church (Matt. 16:18) and the New Testament itself declares the Church to be “the pillar and foundation of the truth” (1 Tim. 3:15).
How would you answer my Muslim friend?