From the Bible:

John 13:34,35: “A new commandment I give unto you, That ye love one another; as I have loved you, that ye also love one another. By this shall all men know that ye are my disciples.”

John 15:12: “This is my commandment, That ye love one another, as I have loved you.”

From the Bhagavad Gita:

“The serene Self, being one with Brahman, neither grieves nor yearns. The same to all, he attains supreme devotion to Me.” (18:54)