The Kitáb-i-Aqdas
8.and when the Sun of Truth and Utterance shall set, turn your faces towards the Spot that We have ordained for you   ¶6
Bahá’u’lláh ordains His resting-place as the Qiblih after His passing. The Most Holy Tomb is at Bahjí, ‘Akká. ‘Abdu’l-Bahá describes that Spot as the “luminous Shrine,” “the place around which circumambulate the Concourse on High.”
In a letter written on his behalf, Shoghi Effendi uses the analogy1 of the plant turning in the direction of the sun to explain the spiritual significance of turning towards the Qiblih:
…just as the plant stretches out to the sunlight—from which it receives life and growth—so we turn our hearts to the Manifestation of God, Bahá’u’lláh, when we pray; … we turn our faces … to where His dust lies on this earth as a symbol of the inner act.
1 Lights of Guidance, p. 465, no. 1523
resting place of Bahá’u’lláh,   144, n7