First Presidency Letter to Mission Presidents; WoW necessary for temple recommends.
Instructions to mission presidents, October 8, 1919, reprinted in James R. Clark (ed.), Messages of the First Presidency, Vol. 5 (Salt Lake City: Bookcraft: 1971), 163
Presidents of Missions are not authorized to give temple recommends; these are issued by the President of the Church for mission members; upon obtaining suitable letters of recommendation from Mission Presidents for such members. Letters of recommendation should be given only to those who have been members of the Church at least a year, and in good standing for one year prior to giving the recommend. It must be known that they keep the Word of Wisdom, pay their tithing and otherwise are good members. Each letter of recommendation should specify what particular blessing the person is recommended to receive.