In Hebrew, emotions and feelings are conveyed through facial expressions. For instance, a “low” face (panim nemukhot) is sad, a “dark” face is angry, a bright face is happy, a “long” face (panim arukhot) is patient, a “strong” face (azut panim) is insolent, and a pale face is ashamed. Poetically, the eyes may be the window to the soul, but to the Hebrew speaker, the face is the mirror of the heart.
So when the scriptural narrative recounts the souring of the relationship between Jacob and Laban, it is no surprise that this change is noted by a metaphor of facial expression. Laban’s children were envious and resentful of Jacob’s newfound wealth. They saw it as his aggrandizement at their father’s expense. No doubt this opinion was shared by Laban as well whose manner towards Jacob changes drastically (Genesis 31:2). The text reports that Jacob saw Laban’s face and he was not with him as he was in the past. Ostensibly, the concluding phrase in the text refers to Laban as well. Jacob understood that by looking into his face that if his face shows unhappiness than Laban was no longer as friendly towards him as he was in the past. This is certainly how the Midrash (Bereshit Rabbah 73:12) sees it. Bar Sira is reported to have said that the changes in a man’s heart, for good or for bad, are revealed through facial expressions. Laban’s attitude had changed and his face confirmed it.
However, it is possible to read the text a little differently. Laban’s face had changed. But in reaction to this observation, it was Jacob who was not with Laban as he was beforehand. It is a subtle but instructive difference. People react to what they see in other people’s faces. As expressed in avot D’Rabbi Natan (Chapter 13), a friendly expression is batter than all the gifts in the world. But an unkind expression is devastating.
Jacob saw Laban’s face and realized they were no longer friends. This realization affected how Jacob treated Laban. Instead of considering Laban a benefactor, he was now a suspected enemy.