Penn's father dying immediately after his liberation, left him a clear estate of L1500 a-year a considerable property in those days. The old man had by this time been brought to regard his son's conduct in a more favorable light than he had done at first; and one of his dying advices to him was, to 'suffer nothing in this world to tempt him to wrong his conscience.'
For twelve months after his father's death Penn proceeded as before, preaching habitually at meetings of persons of his own persuasion, writing tracts and treatises in defense of Quakerism, and on other theological and political topics, among which was an account of the recent trial of himself and Mead, and engaging also in oral controversy with several dissenting preachers who had inveighed against the Quakers from their pulpits. His activity soon brought him into fresh trouble. Towards the end of the year 1671, he was again apprehended on the charge of preaching to an illegal assembly, and brought before Sir John Robinson, lieutenant of the Tower, who was one of his judges on the former trial. Sir Samuel Starling was also present. Unable to convict the prisoner on the conventicle act, Sir John, who was resolved not to let him escape, adopted another plan, and required him to take the oath of allegiance to the king, well knowing that, as it was contrary to the principles of the Quakers to take an oath at all, he would refuse, and thereby subject himself to imprisonment. vow, Mr. Penn,' said Sir John Robinson, on his refusal, am sorry for you. You are an ingenious gentleman; all the world must allow you, and do allow you that; and you have a plentiful estate; why should you render yourself unhappy by associating with such a simple people?"I confess,' said Penn in reply, have made it my choice to relinquish the company of those that are ingeniously wicked, to converse with those that are more honestly simple.' wish you wiser! said Sir John. 'And I wish thee better! ' replied Penn. You have been as bad as other folks,' observed the judge? When and where? ' cried Penn, his blood rising at this accusation of hypocrisy. I charge thee to tell the company to my face. ' Abroad and at home too,' said Sir John. Penn, indignant at this ungenerous taunt, exclaimed, I make this bold challenge to all men, women, and children upon earth, justly to accuse me with having seen me drunk, heard me swear, or speak one obscene word, much less that I ever made it a practice. I speak this to God's glory, who has ever preserved me from the power of these pollutions.' Then turning to his calumniator, and forgetting for a moment his wonted meekness, 'Thy words,' said he, 'shall be thy burden, and I trample thy slander as dirt under my feet!'