Biden's letter to Trump revealed: 'May God bless you and guide you'

"As I take leave of this sacred office I wish you and your family all the best in the next four years. The American people - and people around the world - look to this house for steadiness in the inevitable storms of history, and my prayer is that in the coming years will be a time of prosperity, peace, and grace for our nation.

"May God bless you and guide you as He has blessed and guided our beloved country since our founding."

"He may have. Don't they leave it in the desk? I don't know," Trump told Doocy before discovering the letter. "Thank you, Peter. It could have been years before we found this thing."

On Tuesday, Trump responded to further questions from Doocy about the contents of the letter.

"It was a very nice letter," Trump told reporters. "It was a little bit of an inspirational-type letter. Enjoy it, do a good job. Important, very important. How important the job is."

"It was a positive, for him, in writing it," Trump continued. "I appreciated the letter."

Biden, however, was the first president to find himself in the unique position of writing a letter to someone who is both his successor and the predecessor who left him a note four years earlier. Trump became the first president to serve nonconsecutive terms since Grover Cleveland in the late 1800s.

Biden has said Trump left him a "very generous letter," but has so far declined to share the content of what Trump wrote, deeming it private.

Fox News Digital's Greg Wehner contributed to this report.