Matthew 23:10

Neither be ye called masters: for one is your Master, even Christ.

Cross-reference

In Matthew 23:8, Jesus forbids being called 'rabbi' — the same teaching against human titles of honor, with Christ as the sole teacher.

In Matthew 26:18, Jesus refers to Himself as 'the Teacher' — directly claiming the sole instructor role He asserts here.

In 1 Corinthians 12:5, different services are under the same Lord — reflecting the same principle of one ultimate authority, Christ.