Yājñavalkya Śikṣā 188

188

pakṣau vitatya khe gṛdhro bhrāntyā saṅkacya tiṣṭhati
evaṃ varṇāḥ prayoktavyā vā̱rdhrī̱na̱so nidarśanam

A vulture, having spread its wings in the sky, stays contractedly while wheeling; / thus the speech sounds should be pronounced; vārdhrīnaso is the example.