MOST importantly, this entire dilemma has already been proven in Judaism.
The Pharisees believed in a written Torah AND an oral torah, and it was PRECISELY the oral tradition that Yeshua railed against, calling it "traditions of men". They had bolted on so many rules and regulations that the original Torah was nearly unrecognizable beneath their weight - And yet, it was still far closer to what YHWH commanded than what our legacy through the Roman church has left us.
Yeshua kept the true Torah (the written one), and He kept the Holy Days, as did His disciples. They built their arguments upon the Scriptures, which they revered, as it is plain to see.
He had to have kept the Law, as the very definition of sin IS breaking any part of the Law. That His disciples followed his example sets the same example for us.
This is the quintessential defense of sola-scriptura. Unfortunately, Protestant traditions, many (in fact, most) left over from Rome, make this defense erratic and imperfect.
Amen.
Exo 20:8 Remember the sabbath day, to keep it holy.
Exo 20:9 Six days shalt thou labour, and do all thy work:
Exo 20:10 But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates:
Exo 20:11 For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.