[David O. McKay Office Journal]
President Clark's call to be First Counselor to President McKay. 8:30 a.m.--Following Brother Moyle's departure, I called President Clark and asked him to come to my private office. I said to him: "President Clark, I think the time has come when we should reorganize the First Presidency, and I should like to have you as my First Counselor." "Well, now," he said, "I do not want you to feel obligated to take me, but I feel honored in being asked, and I pledge you my wholehearted suport, and all that I have I want to give to the Cause and to the support of the Church and the First Presidency, and I pledge my allegiance to you." I thanked him, and then told him that I should like to have Brother Henry D. Moyle as my second counselor. President Clark was agreeable and said that Brother Moyle would give good support.
[McKay, David O., Office Journal]