Below passage is in the context of sage Yajnavalkya addressing his wife, Maitreyi.

[Brhadaranyaka Upanishad Translation, 2.4.5, Advaita Ashram]

He said: It is not for the sake of the husband, my dear, that he is loved, but for one’s own sake that he is loved. It is not for the sake of the wife, my dear, that she is loved, but for one’s own sake that she is loved. It is not for the sake of the sons, my dear, that they are loved, but for one’s own sake that they are loved. It is not for the sake of wealth, my dear, that it is loved, but for one’s own sake that it is loved. It is not for the  sake of the Brahmana*, my dear, that he is loved, but for one’s own sake that he is loved. It is not for the sake of the Kshatriya, my dear, that he is loved, but for one’s own sake that he is loved. It is not for the sake of the worlds, my dear, that they are loved, but for one’s own sake that they are loved. It is not for the sake of the gods, my dear, that they are loved, but for one’s own sake that they are loved. It is not for the sake of the beings, my dear, that they are loved, but for one’s own sake that they are loved. It is not for the sake of all, my dear, that all is loved, but for one’s own sake – that it is loved. The Self, my dear Maitreyi, should  be realised-should be heard of, reflected on and meditated upon. By the realisation of the Self, my dear, through hearing, reflection and meditation, all this is known.

*Brahmana here refers to a cast.