Loving other people is one of the foremost, fundamental principles in the Torah. By contrast, the opposite trait, baseless hatred, is an extremely grave sin, to the extent that the Sages maintain that, in terms of its gravity, it is the equivalent of the three cardinal transgressions of idolatry, bloodshed, and immortality.

So said the Holy One, blessed be He, to Israel: My sons, have I withheld anything from you? What do I ask of you? I ask only that you love one another and respect one another, and be fearful of each other, and that there should be no sins, or robbery, or any ugliness between you…so that you will never behave in an unseemly manner, as it is stated: “He told you, man, what is good, and what the Lord demands from you: Only to execute justice, to love kindness, and to walk humbly with your God” (Micah 6:8). Do not read: “Walk humbly with your God” (im Elohekha), but rather interpret the verse: Walk humbly, and your God will be with you (ve’imkha Elohekha). As long as you are with Him [by following His ways] discreetly and humbly, He will be with you discreetly. Therefore, it is stated: “Walk humbly with your God.”

“Love your neighbor as yourself” (Leviticus 19:18). Rabbi Akiva says: This is an essential principle of the Torah.

Why was the First Temple destroyed? Because of three matters that were prevalent during the First Temple period: idol worship, forbidden sexual relations, and bloodshed…. But considering that the people during the Second Temple period were engaged in Torah study, observance of mitzvot, and acts of kindness, and they did not perform the sinful acts that were performed during the First Temple period, why was the Second Temple destroyed? Because there was baseless hatred during that period. This serves to teach you that baseless hatred is the equivalent of the three cardinal transgressions: idol worship, forbidden sexual relations, and bloodshed. (Eliyahu Rabba 26; Sifra, Kedoshim 2; Yoma 9b)