Return, then, and cleave wholly unto God, and cleanse thine heart from the world and all its vanities, and suffer not the love of any stranger to enter and dwell therein. Not until thou dost purify thine heart from every trace of such love can the brightness of the light of God shed its radiance upon it, for to none hath God given more than one heart. This, verily, hath been decreed and written down in His ancient Book. And as the human heart, as fashioned by God, is one and undivided, it behooveth thee to take heed that its affections be, also, one and undivided. Cleave thou, therefore, with the whole affection of thine heart, unto His love, and withdraw it from the love of anyone besides Him, that He may aid thee to immerse thyself in the ocean of His unity, and enable thee to become a true upholder of His oneness....
- Baha’u’llah (Quoted by Shoghi Effendi in ‘The Promised Day Is Come’)