Hiranyakeshigrihyasutra 2.4.10.4

2.4.10.4

agnimupasamādhāya dakṣiṇāprāgagrairdarbhaiḥ paristīryaikapavitrāntarhitāyāmājyasthālyāmājyaṃ saṃskṛtya prasavyaṃ pariṣicyaudumbaramidhmamabhyādhāyaudumbaryā darvyā juhoti \4\

Having put wood on the fire and strewn southward pointed and eastward-pointed Darbha grass around it, having prepared the Âgya in an Âgya pot over which he has laid one purifier, having sprinkled water round (the fire) from right to left, and put a piece of Udumbara wood on (the fire), he sacrifices with the (spoon called) Darvi which is made of Udumbara wood.