Kabbalah zu Bereschit 30:27

Rabbi Yehuda said that this should have been true of Laban as well, because he was also a sorcerer, as it is written, "I have learned by signs that Hashem has blessed me for your sake" (Gen. 30:27). And although Jacob was a plain and whole man, he was merciful with whomever he had to be merciful with. He was strict in judgment and deceitful when necessary. For he consisted of two parts. It is written of him, "With the merciful you will show yourself merciful; and with the perverse you will show yourself subtle" (Tehilim 18:26), which means that with the merciful on the side of Chesed, and with the perverse on the side of Strict Judgment, all as it ought to be.