Source of the Anecdote?

From Things That Can't Change by George Weigel:

When the Second Vatican Council was putting the finishing touches on one of its key documents, the Dogmatic Constitution on the Church (Lumen Gentium), Pope Paul VI proposed that it include a statement that the pope is “accountable to the Lord alone.”

The suggestion was referred to the Council’s Theological Commission, which, perhaps to Pope Paul’s surprise, flatly rejected it: the Roman Pontiff, the Theological Commission noted, “is . . . bound to revelation itself, to the fundamental structure of the Church, to the sacraments, to the definitions of earlier Councils, and other obligations too numerous to mention.” The pope cannot, in other words, change the deposit of faith, of which he is the custodian, not the master. The pope can’t decide that the Church can do without bishops, or that there really are eleven sacraments, or that Arius had it right in denying the divinity of Christ.