October 21

They [members of a spiritual assembly] must then proceed with the utmost devotion, courtesy, dignity, care and moderation to express their views. They must in every matter search out the truth and not insist upon their own opinion, for stubbornness and persistence in one’s views will lead ultimately to discord and wrangling and the truth will remain hidden. The honored members must with all freedom express their own thoughts, and it is in no wise permissible for one to belittle the thought of another, nay, he must with moderation set forth the truth, and should differences of opinion arise a majority of voices must prevail, and all must obey and submit to the majority. It is again not permitted that any one of the honored members object to or censure, whether in or out of the meeting, any decision arrived at previously, though that decision be not right, for such criticism would prevent any decision from being enforced. 
(‘Abdu’l-Baha, quoted by Shoghi Effendi, from a letter dated March 5, 1922; ‘Baha’i Administration’)