“Yehoshua ben Levi asked: ‘What is the meaning of: And this is the teaching which Moses שָׂם [sam] set, before the children of Israel [Deuteronomy 4:44]?’ – If he is meritorious it becomes for him סַם [sam], medicine, of life, if not, deadly סַם [sam], poison” (BT Yoma 72b, cf. BT Ta’anit 7a).
If you find honey, eat just what you need, lest you have your fill of it and throw it up (Proverbs 25:16).
“Marveling at the power of water to wear away a hard rock Akiva said, ‘If that which is soft can engrave that which is hard, then the words of Torah which are like steel can certainly penetrate my heart which is but flesh and blood.’ They replied, ‘Akiva, have you not read Water wears away stones [Job 14:19].’ He then went together with his son and they appeared before an elementary teacher. Said Akiva to him: ‘Master, teach me Torah.’ Akiva took one end of the tablet, and his son the other end of the tablet. The teacher wrote down the aleph bet for him and he learned it; aleph tav, and he learned it; the book of Leviticus, and he learned it. He went on studying until he learned the whole Torah. Then he went and appeared before Rabbi Eliezer and Rabbi Yehoshua. ‘My masters,’ he said to them, ‘reveal the justification of Mishnah to me.’ When they told him one halakhah he went off to be by himself. ‘This aleph,’ he wondered, ‘why was it written? This bet, why was it written? This thing, why was it said?’ He came back and asked them, and reduced them to silence” (Avot de Rabbi Nathan A6).
“He said, ‘Let me go, for dawn has risen! [Genesis 32:27]. Rabbi Yehudah opened, Who is this looking forth like the dawn, fair as the moon, bright as the sun…? [Song of Songs 6:10]. This verse has been established and explained, but Who is this looking forth? – Israel, when the blessed Holy One will raise them, bringing them out of exile. He will then open for them a tiny crack of light, then another opening, wider, until the blessed Holy One opens for them supernal gates facing four directions of the world. So with all the blessed Holy One does for Israel and for the righteous among them – always so, never all at once. This can be compared to a person thrown into darkness, dwelling in darkness constantly. When they want to illumine him, they must open the light to him like the eye of a needle, then wider, always gradually, until he is illumined with all the light fittingly. Similarly with Israel, as is said: Little by little I will drive them out before you [Exodus 23:30]. And so with one who is being cured: not all at once, but little by little, until he is fortified.
But with Esau, not so! Rather, he is illumined all at once and deprived little by little, until Israel are fortified and eliminate him entirely from this world and from the world that is coming. Since he blazed all at once, he is annihilated completely, whereas Israel’s light increases little by little until they are invigorated and the blessed Holy One illumines them forever. Everyone asks, Who is this looking forth like the dawn? – at first a subtle glow; then fair as the moon, then bright as the sun, then awesome as bannered hosts [Song of Songs ibid.] – Beaming powerfully, intensely, fittingly” (Zohar 1:170a).