You have this backward:
He did not use tradition; he merely referenced it, and showed how it fit with scripture.
Very well. Going to the topic of this thread and the silliness of suggesting the Roman Church arbitrarily changed the Sabbath:
It is written that The Lord is Lord of the Sabbath. Hence he can do what he wishes.
It is written that The Lord appeared to the disciples behind locked doors on the first day of the week. Hence on Sunday.
It is also written that The Lord appeared again one week later. Again on Sunday.
It is also written that the Holy Spirit descended upon the disciples on the 7th Sunday after Easter (Pentecost - the 50th day).
Clearly The Lord let the disciples become accustomed to seeing Him on Sunday … The Day of the Resurrection and The Lords Day.
Finally, it is written that the apostles usually gathered on Sunday to break bread. Hence following the tradition that The Lord began.
If you need verses, please let me know.