Kamasutra 4.2.67

4.2.67

puruṣas tu bahūn dārān samāhṛtya samo bhavet/
na cāvajñāṃ cared āsu vyalīkān na saheta ca//

A man marrying many wives should act fairly towards them all. He should neither disregard nor pass over their faults, and should not reveal to one wife the love, passion, bodily blemishes, and confidential reproaches of the other. No opportunity should be given to any one of them of speaking to him about their rivals, and if one of them should begin to speak ill of another, he should chide her and tell her that she has exactly the same blemishes in her character. One of them he should please by secret confidence, another by secret respect, and another by secret flattery, and he should please them all by going to gardens, by amusements, by presents, by honoring their relations, by telling them secrets, and lastly by loving unions. A young woman who is of a good temper, and who conducts herself according to the precepts of the Holy Writ wins her husband’s attachment, and obtains a superiority over her rivals.