Everything that is hath come to be through His irresistible decree. Whenever My laws appear like the sun in the heaven of Mine utterance, they must be faithfully obeyed by all, though My decree be such as to cause the heaven of every religion to be cleft asunder. He doeth what He pleaseth. He chooseth, and none may question His choice. Whatsoever He, the Well-Beloved, ordaineth, the same is, verily, beloved. To this He Who is the Lord of all creation beareth Me witness. Whoso hath inhaled the sweet fragrance of the All-Merciful, and recognized the Source of this utterance, will welcome with his own eyes the shafts of the enemy, that he may establish the truth of the laws of God amongst men. Well is it with him that hath turned thereunto, and apprehended the meaning of His decisive decree.

God hath imposed a fine on every adulterer and adulteress, to be paid to the House of Justice: nine mithqáls of gold, to be doubled if they should repeat the offence. Such is the penalty which He Who is the Lord of Names hath assigned them in this world; and in the world to come He hath ordained for them a humiliating torment. Should anyone be afflicted by a sin, it behoveth him to repent thereof and return unto his Lord. He, verily, granteth forgiveness unto whomsoever He willeth, and none may question that which it pleaseth Him to ordain. He is, in truth, the Ever-Forgiving, the Almighty, the All-Praised.

In the Bayán it had been forbidden you to ask Us questions. The Lord hath now relieved you of this prohibition, that ye may be free to ask what you need to ask, but not such idle questions as those on which the men of former times were wont to dwell. Fear God, and be ye of the righteous! Ask ye that which shall be of profit to you in the Cause of God and His dominion, for the portals of His tender compassion have been opened before all who dwell in heaven and on earth.

Were He to decree as lawful the thing which from time immemorial had been forbidden, and forbid that which had, at all times, been regarded as lawful, to none is given the right to question His authority. Whoso will hesitate, though it be for less than a moment, should be regarded as a transgressor.

In the Bayán it had been forbidden you to ask Us questions.
The Báb forbade His followers to ask questions of Him Whom God will make manifest (Bahá’u’lláh), unless their questions were submitted in writing and pertained to subjects worthy of His lofty station. See Selections from the Writings of the Báb.
Bahá’u’lláh removes this prohibition of the Báb. He invites the believers to ask such questions as they “need to ask”, and He cautions them to refrain from posing “idle questions” of the kind which preoccupied “the men of former times”.