EXTRA · Parashas Vayeishev · Passuk 37:6 · not a Torah Temimah citation on this passuk
He said to them, “Hear this dream that I have dreamed:
Classical source (EXTRA side-ring): Yalkut Shimoni 141 / Shabbos 10b theme.
Sefaria — Yalkut Shimoni 141 / Shabbos 10b theme
English: Rav said: A person should never treat one child differently from the others, for because of two sela’ weight of fine wool that Yaakov added for Yosef beyond his other sons, they became jealous of him, and the matter rolled on until our ancestors went down to Mitzrayim.
Derash on the verse (Bavli/Yalkut) — not a formal named middah of the 13. A small parental preference is traced as the spark of a national descent.
Favoring one child, even with a small gift, can set jealousy in motion with historic consequences.