I said, "God said to trust no man for what they speak, but to test the spirits that are speaking whether they be of truth or error, 1 John 4:1-6.Where does God say this?
1Co 12:28 And God has appointed in the church first apostles, second prophets, third teachers, then miracles, then gifts of healing, helping, administrating, and various kinds of tongues.
1Co 12:29 Are all apostles? Are all prophets? Are all teachers? Do all work miracles? (ESV)
Gal 6:6 Let the one who is taught the word share all good things with the one who teaches. (ESV)
Eph 4:11 And he gave the apostles, the prophets, the evangelists, the shepherds and teachers,
Eph 4:12 to equip the saints for the work of ministry, for building up the body of Christ,
Eph 4:13 until we all attain to the unity of the faith and of the knowledge of the Son of God, to mature manhood, to the measure of the stature of the fullness of Christ,
Eph 4:14 so that we may no longer be children, tossed to and fro by the waves and carried about by every wind of doctrine, by human cunning, by craftiness in deceitful schemes. (ESV)
Col 3:16 Let the word of Christ dwell in you richly, teaching and admonishing one another in all wisdom, singing psalms and hymns and spiritual songs, with thankfulness in your hearts to God. (ESV)
1Ti 3:2 Therefore an overseer must be above reproach, the husband of one wife, sober-minded, self-controlled, respectable, hospitable, able to teach, (ESV)
1Ti 4:13 Until I come, devote yourself to the public reading of Scripture, to exhortation, to teaching. (ESV)
1Ti 5:17 Let the elders who rule well be considered worthy of double honor, especially those who labor in preaching and teaching. (ESV)
2Ti 2:2 and what you have heard from me in the presence of many witnesses entrust to faithful men, who will be able to teach others also.
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2Ti 2:24 And the Lord's servant must not be quarrelsome but kind to everyone, able to teach, patiently enduring evil,
2Ti 2:25 correcting his opponents with gentleness. God may perhaps grant them repentance leading to a knowledge of the truth, (ESV)
2Ti 3:16 All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness,
2Ti 3:17 that the man of God may be complete, equipped for every good work. (ESV)
Tit 2:1 But as for you, teach what accords with sound doctrine. (ESV)
Heb 5:12 For though by this time you ought to be teachers, you need someone to teach you again the basic principles of the oracles of God. You need milk, not solid food, (ESV)
So, there are a number of passages that speak of God gifting some to teach, that teaching needs to be in line with sound doctrine, and that teachers are to teach others how to teach. To be certain, there are also a number of warnings against false teachings and false teachers.
But, given the good things said about teaching, about its necessity, and that it is given by God, why would God then contradict himself by telling "us to not trust a mans teaching"? That would mean God told us not to trust the very system he put in place for teaching sound doctrine in the Church. Maybe I misunderstood what you meant.
If you would have read the rest of that sentence you would know what I meant.