There are no new teachings, just clarifications of old ones.
For example, when controversy arose in the Church regarding whether the observance of the Torah was binding on Gentile converts it was a matter of debate among the Apostles - who then settled it definitively.
Another salient example is the Canon of the New Testament itself. There was no definitive list of which books made up the NT until the Church ruled on it early in the300s - almost 250 years after Paul wrote! This was not a matter of new teaching - it was amatter of defining the traditional canon of Scripture.
Romans 8:27
And he who searches our hearts knows the mind of the Spirit, because the Spirit intercedes for the saints in accordance with God's will.
James 5:16
Confess your faults one to another, and pray one for another, that ye may be healed. The effectual fervent prayer of a righteous man availeth much.