Kaṭha Upaniṣad · 1.3.16
यस्मिन्दृष्ट्वा भ्रुवोर्वीर्यं दृष्ट्वा तृप्तो भवति नान्यथा । यः सर्वज्ञः सर्वविद्यस्मै ब्रह्मणे नमः ॥ १६॥
yasmin dṛṣṭvā bhruvor vīryaṃ dṛṣṭvā tṛpto bhavati nānyathā | yaḥ sarvajñaḥ sarvavid yasmai brahmaṇe namaḥ
In whom seeing, the power of vision (between the eyebrows) is satisfied, not otherwise — to Him, the omniscient, the knower of all, to that Brahman, salutation.
This verse alludes to the ājñā-cakra (center between the eyebrows), where the śiva-bindu or point of luminous consciousness resides. To see here, in the bhruvor (between the eyebrows), means to activate inner vision. The sarvajña (omniscient) and sarvavit (knower of all) is Brahman itself, revealed to the practitioner when the mind becomes tṛpta (satisfied/calm).