Rigveda 2.4.6
आ यो वना॑ तातृषा॒णो न भाति॒ वार्ण प॒था रथ्ये॑व स्वानीत् ।कृ॒ष्णाध्वा॒ तपू॑ र॒ण्वश्चि॑केत॒ द्यौरि॑व॒ स्मय॑मानो॒ नभो॑भिः॥
ā yo vanā tātṛṣāṇo na bhāti vārṇa pathā rathyeva svānīt |kṛṣṇādhvā tapū raṇvaściketa dyauriva smayamāno nabhobhiḥ ||
Our plain-language meaning of this verse is waiting for scholar review.