Rabbi Hoshaya said: Whoever makes himself wholehearted, the hour stands in his favor, as it says, “Walk before Me and be wholehearted” (Bereishis 17:1), and it is written, “And you will be the father of a multitude of nations” (Bereishis 17:4).

Rebbi said: Whoever practices divination, divination [comes upon] him, as it says, “For there is no divination [lo nachash] in Yaakov” (Bamidbar 23:23). But is it not written with lamed alef [lo, “no,” and not lo, “to him”]? Rather, [it comes upon him] measure for measure.

Ahavah the son of Rabbi Ze’ira taught: Any person who does not practice divination is brought into a partition that even the ministering angels cannot enter, as it says, “For there is no divination in Yaakov and no sorcery in Yisrael, etc.” (Bamidbar 23:23).1