Your father. This was the title given to eminent teachers and founders of schools, to whom the people were taught to look up rather than to God. It was also addressed to prophets (2 Kings 2:12; 2 Kings 6:21).
In Matthew 23:8 Christ said, "be not called;" here he uses the active, "call not," as if he would intimate that his followers must not give this honoured title to any doctor out of complaisance, or flattery, or affectation.
Upon the earth. In contradistinction to heaven, where our true Father dwells. They were to follow no earthly school. They had natural lathers and spiritual fathers, but the authority of all comes from God; it is delegated, not essential; and good teachers would make men look to God, and not to themselves, as the source of power and truth.