Said about az-Zubayr at a time for which it was appropriate
He asserts that he swore allegiance to me with his hand but did not swear with his heart. (1) So he does admit allegiance.
As regards his claiming it otherwise than with his heart he should come forward with a clear argument for it. Otherwise, he should return to wherefrom he has gone out. (2)
(1). When after swearing allegiance on the hand of Amir al-mu'minin, az-Zubayr ibn al-`Awwam broke the allegiance, then sometimes he put forth the excuse that he was forced to swear allegiance and that forced allegiance is no allegiance, and sometimes he said that allegiance was only for show. His heart did not go in accord with it.
As though he himself admitted with his tongue the duplicity of his outer appearance and inner self. But this excuse is like that of the one who reverts to apostasy after adopting Islam and to avoid penalty may say that he had accepted Islam only by the tongue, not in the heart.
Obviously, such an excuse cannot be heard, nor can avoid punishment by this argument. If az-Zubayr suspected that `Uthman was slain at Amir al-mu'minin's insistence, this suspicion should have existed when he was taking oath for obedience and stretching his hand for allegiance, not now that his expectations were getting frustrated and hopes had started dawning from somewhere else.
(2). Amir al-mu'minin has rejected his claim in short form thus: that when he admits that his hands had paid allegiance then until there is justification for breaking of the allegiance he should stick to it. But if, according to him his heart was not in accord with it he should produce other proof for it.
Since proof about the state of heart cannot be adduced how can he bring such proof, and an assertion without proof is unacceptable to his mind.