November 26

...the power of the Covenant will protect the Cause of Bahá'u'lláh from the doubts of the people of error. It is the fortified fortress of the Cause of God and the firm pillar of the religion of God. Today no power can conserve the oneness of the Bahá'í world save the Covenant of God; otherwise differences like unto a most great tempest will encompass the Bahá'í world. It is evident that the axis of the oneness of the world of humanity is the power of the Covenant and nothing else.... Therefore, in the beginning the believers must make their steps firm in the Covenant so that the confirmations of Bahá'u'lláh may encircle them from all sides, the cohorts of the Supreme Concourse may become their supporters and helpers, and the exhortations and advices of 'Abdu'l-Bahá, like unto the pictures engraved on stone, may remain permanent and ineffaceable in the tablets of all hearts.  
(‘Abdu’l-Baha, ‘Tablets of the Divine Plan Revealed by 'Abdu'l-Bahá to the North American Bahá'ís’; The Compilation of Compilations, vol. I, The Covenant)