God hath decreed, in token of His mercy unto His creatures, that semen is not unclean. Yield thanks unto Him with joy and radiance, and follow not such as are remote from the Dawning-place of His nearness. Arise ye, under all conditions, to render service to the Cause, for God will assuredly assist you through the power of His sovereignty which overshadoweth the worlds. Cleave ye unto the cord of refinement with such tenacity as to allow no trace of dirt to be seen upon your garments. Such is the injunction of One Who is sanctified above all refinement. Whoso falleth short of this standard with good reason shall incur no blame. God, verily, is the Forgiving, the Merciful. Wash ye every soiled thing with water that hath undergone no alteration in any one of the three respects; take heed not to use water that hath been altered through exposure to the air or to some other agent. Be ye the very essence of cleanliness amongst mankind. This, truly, is what your Lord, the Incomparable, the All-Wise, desireth for you.

They who recite the verses of the All-Merciful in the most melodious of tones will perceive in them that with which the sovereignty of earth and heaven can never be compared. From them they will inhale the divine fragrance of My worlds -- worlds which today none can discern save those who have been endowed with vision through this sublime, this beauteous Revelation. Say: These verses draw hearts that are pure unto those spiritual worlds that can neither be expressed in words nor intimated by allusion. Blessed be those who hearken.

Behold, the "mystery of the Great Reversal in the Sign of the Sovereign" hath now been made manifest. Well is it with him whom God hath aided to recognize the "Six" raised up by virtue of this "Upright Alif"; he, verily, is of those whose faith is true. How many the outwardly pious who have turned away, and how many the wayward who have drawn nigh, exclaiming: "All praise be to Thee, O Thou the Desire of the worlds!" In truth, it is in the hand of God to give what He willeth to whomsoever He willeth, and to withhold what He pleaseth from whomsoever He may wish. He knoweth the inner secrets of the hearts and the meaning hidden in a mocker’s wink. How many an embodiment of heedlessness who came unto Us with purity of heart have We established upon the seat of Our acceptance; and how many an exponent of wisdom have We in all justice consigned to the fire. We are, in truth, the One to judge. He it is Who is the manifestation of "God doeth whatsoever He pleaseth", and abideth upon the throne of "He ordaineth whatsoever He chooseth".

O Pen of the Most High! Move Thou upon the Tablet at the bidding of Thy Lord, the Creator of the Heavens, and tell of the time when He Who is the Dayspring of Divine Unity purposed to direct His steps towards the School of Transcendent Oneness; haply the pure in heart may gain thereby a glimpse, be it as small as a needle’s eye, of the mysteries of Thy Lord, the Almighty, the Omniscient, that lie concealed behind the veils. Say: We, indeed, set foot within the School of inner meaning and explanation when all created things were unaware. We saw the words sent down by Him Who is the All-Merciful, and We accepted the verses of God, the Help in Peril, the Self-Subsisting, which He [The Báb] presented unto Us, and hearkened unto that which He had solemnly affirmed in the Tablet. This we assuredly did behold. And We assented to His wish through Our behest, for truly We are potent to command.

Beware lest aught that hath been revealed in the Bayán should keep you from your Lord, the Most Compassionate. God is My witness that the Bayán was sent down for no other purpose than to celebrate My praise, did ye but know! In it the pure in heart will find only the fragrance of My love, only My Name that overshadoweth all that seeth and is seen. Say: Turn ye, O people, unto that which hath proceeded from My Most Exalted Pen. Should ye inhale therefrom the fragrance of God, set not yourselves against Him, nor deny yourselves a portion of His gracious favour and His manifold bestowals. Thus doth your Lord admonish you; He, verily, is the Counsellor, the Omniscient.

Wash ye every soiled thing with water that hath undergone no alteration in any one of the three respects
The “three respects” referred to in this verse are changes in the colour, taste or smell of the water. Bahá’u’lláh provides additional guidance concerning pure water and the point at which it is considered unsuitable for use (Q&A 91).

Question: Concerning pure water, and the point at which it is considered used.
Answer: Small quantities of water, such as one cupful, or even two or three, must be considered used after a single washing of the face and hands. But a kurr [this refers to a volume of approximately one half of a cubic metre] or more of water remaineth unchanged after one or two washings of the face, and there is no objection to its use unless it is altered in one of the three ways [colour, taste and smell], for example its colour is changed, in which case it should be looked upon as used.