Rabbi Roodyn

י) אֹהֲבֵי ה’ שִׂנְאוּ רָע שֹׁמֵר נַפְשׁוֹת חֲסִידָיו מִיַּד רְשָׁעִים יַצִּילֵם:

You who love Hashem, hate evil; He watches the souls of His pious ones, He rescues them from the hands of the wicked.

The Malbim explains that after having explained throughout the chapter that the nations of the world operate according to a system of hashgacha klalis ostensibly governed by Hashem operating through the laws of nature, the psalmist then turns his attention to the Jewish people.

This pasuk is saying that the Jewish people are like children under their father’s close supervision, who takes care of all their needs with the utmost love. As recipients of that love, we are in turn called ohavei Hashem, returning His love with ours. Since Hashem is the ultimate good, it makes sense that we need to develop a sense of hatred towards evil.

This sense of closeness is felt most when we appreciate that Hashem watches the souls of His pious ones. His love for us is most closely associated with the nefesh soul which is a part of the Divine. He guards each soul especially protecting them from the malevolent choices of those who choose to abuse their free will.