The works of Ādi Śaṅkarācārya

Viṣṇusahasranāmastotram

Verse 225

इति श्वेताश्वतरोपनिषन्मन्त्रवर्णात् हरौ गुरौ च परा भक्तिः कार्येति ॥

In plain words

So it stands, on the strength of the Śvetāśvatara Upaniṣad's own words: the highest devotion is to be given to Hari and to the teacher alike.

Close to the Sanskrit

Thus — from the very wording of the mantra of the Śvetāśvatara Upaniṣad — toward Hari and toward the guru supreme devotion is to be practised: thus.