Kindness

The First Doctor thanked Joseph Longfoot for his kindness and diligence. In return for the Doctor's kindness in fixing his finger, Longfoot gave the Doctor clues to the location of Avery's treasure. (TV: The Smugglers)

The Twelfth Doctor reassured Alit that she was just being kind when she showed Bill Potts her reflection. He also told and  that he was helping the Mondasians due to it being a kind thing. (TV: The Doctor Falls)

In a speech to the Thirteenth Doctor, the Twelfth Doctor told them to be kind. (TV: Twice Upon a Time)