Scripture does teach us that if the apostles didnt teach it then we are to consider it accursed.
But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed. As we said before, so say I now again, If any man preach any other gospel unto you than that ye have received, let him be accursed. Galatians 1:8-9<<
So would you please show us any infallible source for what the apostles taught other than found in scripture?
True enough. However that scriptural passage refers to what Paul had already taught in his role as a bishop and part of the magisterium i.e., Sacred Tradition.
So would you please show us any infallible source for what the apostles taught other than found in scripture?
Fallacious question. Sacred Tradition and Sacred Scripture are in harmony. This question presumes separation between the two when there is none. An unfortunate side-effect of protestanatism. The either/or dilemma.