The following mantra for the sun is from the Iṡopaniṣad.

You can choose to listen or recite along. We invite you to take a steady and upright posture, comfortable and open. Take a few breaths and let your energy and attention settle. When you feel ready, press play and let these sacred sounds move through your entire being, whether you are listening or singing.

हिरण्मयेन पात्रेण सत्यस्यापिहितं मुखम् ।
 
तत्त्वं पूषन्नपावृणु सत्यधर्माय दृष्टये ॥

hiraṇmayena pātreṇa satyasyāpihitaṃ mukham |

tattvaṃ pūṣannapāvṛṇu satyadharmāya dṛṣṭaye ||

Translation:
The face of the Truth is hidden behind [your] effulgent golden veil. O Pūṣan, sustainer of all life, please remove it and make yourself visible for the sake of true Dharma!

Word-by-Word Translation
hiraṇmayena = with a golden effulgence
pātreṇa = plate, leaf, vessel, pot
satyasya = of the Truth 

apihitam = covered 

mukham = the face

tat = that (plate, leaf, vessel, pot)
tvam = you
pūṣan = Pūṣan, O sustainer
apāvṛṇu = please remove
satyadharmāya = for the true dharma
dṛṣṭaye = for the vision

Teachers: Dr. Maitreya Larios and Shambhavi Dandekar