EXTRA · Parashas Vayeishev · Passuk 37:11 · not a Torah Temimah citation on this passuk
So his brothers were wrought up at him, and his father kept the matter in mind.
Classical source (EXTRA side-ring): Bereshis Rabbah 84:11.
Sefaria — Bereshis Rabbah 84:11
English: “And his father kept the matter” — R’ Levi said: he postponed the moment [for later]. R’ Yochanan said: he took a quill and wrote down on which day, at which hour, and in which place.
Derash on the verse (Bereshis Rabbah) — not a formal named middah of the 13. “Kept the matter” is read as deliberate preservation.
Yaakov neither rejects nor publicizes the dream; he holds it in memory (or writing) until events prove it.