Which of the following is not an essential ingredient of holding out u/s 28 of the Partnership Act?

Section 28 of the Indian Partnership Act, 1932 makes a person liable as a partner by holding out where he represents himself, or knowingly permits himself to be represented, as a partner, and a third person gives credit to the firm on the faith of that representation. Knowledge of the representation is therefore essential, and "Representation without knowledge" is not an ingredient: a representation made without the person's knowledge does not make him liable.