It is forbidden to practice soothsaying as idolaters do, as [Leviticus 19:26] states: "Do not act as a soothsayer."
What is meant by a soothsayer? For example, those who say: Since my piece of bread fell out of my mouth, or my staff fell from my hand, I will not travel to this place today, since if I were to go I would not be able to accomplish my desires.
Since a fox passed on my right side, I will not go out of my door today, since if I were to go out I would meet a deceiver.
Similarly, [this category includes] those who hear the chirping of a bird and say: This will happen or this will not happen; it is beneficial to do this or it is detrimental to do this. [Also, it includes] those who say: Slaughter this rooster that crowed like a raven; slaughter this hen that crowed like a rooster.
Similarly, a person who sets up omens for himself; e.g., if this and this happens, I will do this. If it will not happen, I will not do it, as Eliezer, the servant of Abraham did, and the things of the like - all this is forbidden. Anyone who does one of these things because of such omens is [liable for] lashes.