Franklin Roosevelt actually said...
A post allowance granted to an officer or employee is available only during the part of the fiscal year in which he remains within the district to which he is assigned, except in those cases in which the Secretary of State, in his discretion, may determine otherwise with respect to post allowances payable since July 1, 1940.
Context
Executive Order 8878—Amendment of Executive Order No. 5643 of June 8, 1931, Prescribing Regulations Governing Representation...
08/28/1941