Agni Is the two the sacred hearth and also the deity of that fire who transmits oblations to another deities. Thus, this mantra is recited although invoking the deity Agni in the shape of hearth as witness towards the vow. Agne vratapate vrataṃ cariṣyāmi (Vājasaneyī-Saṃhitā on the Śukla [White] Yajurveda https://www.instagram.com/tantramantraaurvigyaan/