As you know the beloved Guardian highly reprobated resignation from any office to which a believer has been elected and it is certainly best, at this present state of the Cause, for the friends to accept elective service whenever they are called upon to do so. However, there is no objection for an overburdened believer asking the Spiritual Assembly to which he may be elected not to appoint him as an officer or to a committee.
(Universal House of Justice, NSA USA - Developing Distinctive Bahá’í Communities)
We have also been asked to point out that although it is the obligation of a Bahá’í to serve on an Assembly, either Local or National, when elected, on several occasions the beloved Guardian pointed out that before the election of officers, if any member had a good reason in his own opinion why he should not be elected to one of the offices of the Assembly, he was free to suggest that he should not be so elected.
(Compilations, NSA USA - Developing Distinctive Bahá’í Communities)