Dr. Shippen sought Rush's resignation and received it by the end of the month after Continental Congress delegate John Witherspoon, chairman of a committee to investigate Morgan's and Rush's charges of misappropriation and mismanagement against Shippen, told Rush his complaints would not produce reform. Rush later expressed regret for his gossip against Washington. In a letter to John Adams in 1812, Rush wrote, "He was the highly favored instrument whose patriotism and name contributed greatly to the establishment of the independence of the United States." Rush also successfully pleaded with Washington's biographers Justice Bushrod Washington and Chief Justice John Marshall to delete his association with those stinging words.