The Iliad by Homer Book 1 Page 33

Jove sat for a while silent, and without a word, but Thetis still kept firm hold of his knees, and besought him a second time. “Incline your head,” said she, “and promise me surely, or else deny me — for you have nothing to fear — that I may learn how greatly you disdain me.”

At this Jove was much troubled and answered, “I shall have trouble if you set me quarrelling with Juno, for she will provoke me with her taunting speeches; even now she is always railing at me before the other gods and accusing me of giving aid to the Trojans. Go back now, lest she should find out. I will consider the matter, and will bring it about as you wish. See, I incline my head that you may believe me. This is the most solemn promise that I can give to any god.