Agniveshyagrihyasutra 3.8.3.4

3.8.3.4

ya etasyai diśaḥ parābhavannaghāyavo yathā te nābhavān punaḥ iti paścāt kāśastambaṃ darbhāṇāṃ stambamāhara pitṛṇāmoṣadhīṃ priyām \

so that those malicious ones who were ruined from this direction do not exist again'—thus in the west, a clump of kāśa grass; 'Bring a clump of darbha grass, the herb dear to the Fathers;