What did Yakov see on the face of Lavan?
Seforno: He saw that he had accepted the Lashon ha'Ra that Lavan's sons had spoken about him 1 (in the previous Pasuk).
This was remarkable, bearing in mind that, when Yakov arrived, Lavan had no sons, and they were only born thanks to Yakov
Since Hashem will command Yakov to return (verse 3), why must the Torah teach that he saw the hatred of Lavan and his sons?
Ohr ha'Chayim: Had he not known the hatred, he would have left openly. Had Hashem not told him, he would have thought how to find favor with him, and delayed there.
Why does it say that he heard the words of Lavan's sons, and he saw Lavan's face?
Malbim: (He explicitly heard Lavan's sons' gripes.) He saw Lavan's face, and understood that also he suspects Yakov.
Lavan's sons were three days journey away, tending the animals that Lavan took (30:36). Yakov heard others repeat their words. Lavan was nearby. (PF)