I desire to conduct the affairs of this administration that if at the end, when I come to lay down the reins of power, I have lost every other friend on earth, I shall at least have one friend left, and that friend shall be down inside of me.

Abraham Lincoln (1809-1865) American lawyer, politician, US President (1861-65)

Speech (1863-09-30) to the Missouri Committee of Seventy
    (Source)

A committee of seventy "Radical Union Men of Missouri," selected by a state convention, visited Lincoln in the White House, demanding immediate abolition of slavery in the border states, the recruitment of Black soldiers to the Union Army, and that action be taken regarding the factional conflicts (Radicals vs Conservatives) stirred up by the state governor and the US military governor overseeing the state militia. This was Lincoln's concluding remark in reply to the committee's petition.

This was not a prepared speech, so there is no "official" version. These words were later reported by Enos Clarke, one of the committee members, as recorded in Ida Tarbell's The Life of Abraham Lincoln (1895). Tarbell's book was a best-seller, and the quotation is usually given as above.

However, Clarke's report as recorded by Walter Stevens in the Missouri State Historical Society book Lincoln and Missouri (1916) is a bit different:

It is my ambition and desire to so administer the affairs of the government while I remain President that if at the end I shall have lost every other friend on earth I shall at least have one friend remaining and that one shall be down inside of me.

The difference between the two may be between different instances across the years of Clarke reporting on Lincoln's comments. Neither Tarbell nor Stevens give notes as to when and where their statements from Clarke derive.