TT #10 · Parashas Vayigash · Passuk 45:26
And they told him, saying, “Yosef is still alive, and he is ruler over all the land of Egypt.” And his heart went numb, for he did not believe them.
Torah Temimah points to Avot de-Rabbi Natan 30:4.
TT lemma: כי לא האמין להם.
Sefaria — Avot de-Rabbi Natan 30:4
English: Rabbi Shimon said: Such is the punishment of a liar — that even when he speaks the truth, no one listens to him. So we find with the sons of Yaakov: it is said, “He recognized it and said, ‘It is my son’s tunic’” — therefore later, even though they spoke the truth, he did not believe them, as it is said, “and his heart went numb, for he did not believe them.”
Derash on the verse (Avot de-Rabbi Natan) — not a formal named middah of the 13.
One who has previously lied loses credibility even when he later speaks the truth; Yaakov’s initial disbelief is the consequence of the brothers’ earlier deception.