Go your way.
There is nothing in the scripture that prohibits teaching on subjects not contained in the scripture. Aspects of liturgy and prayer are such teaching. But there are references to the teaching authority of the apostolic church, and I gave them to you.
Broader, the concept of Sola Scriptura is not scriptural either, even though, of course, there are multiple passages where the importance of the scripture is proclaimed.
You evade the challenge because you cannot meet it. You may have convinced yourself that the sola scriptura and prohibition on intercessory prayer is somewhere in the scripture, but the actual scripture does not say it. This is why it is a superstition: a metaphysical belief based on a traditional authority that cannot be objectively proven.