The Kitáb-i-Aqdas - The Most Holy Book
Index term: parents, consent to marriage, under Non-Bahá’í­(s)
n92.
We have conditioned it . . . upon the permission of their parents
In a letter written on his behalf, Shoghi Effendi has commented on this provision of the law:

Bahá’u’lláh has clearly stated the consent of all living parents is required for a Bahá’í­ marriage. This applies whether the parents are Bahá’í­s or non-Bahá’í­s, divorced for years or not. This great law He has laid down to strengthen the social fabric, to knit closer the ties of the home, to place a certain gratitude and respect in the hearts of the children for those who have given them life and sent their souls out on the eternal journey towards their Creator.