Note 52 — Chapter XX
Reading edition
Lincoln addressed most of his friends by their family name, seldom prefixing "Mr." A few he called by their first name. Herndon he called "Billy." Ward Hill Lamon he addressed as "Hill." Some of his friends called him "Lincoln," but most of them, "Mr. Lincoln." If any habitually addressed him as "Abe," the author has been unable to learn the fact.
"Although I have heard of cheap fellows, professing that they were wont to address him as 'Abe,' I never knew any one who did it in his presence. Lincoln disdained ceremony, but he gave no license for being called 'Abe'." Whitney: Life on the Circuit with Lincoln, p. 53.