Skandapurana 5.112.44

5.112.44

sadeva niyatāḥ saṃtaḥ śāṃtāḥ ṣoḍaśa te dvijāḥ ..
upahārāḥ sadā preṣyāstvayā bhaktyā mahīpate ..
māsāṃte cābhiṣekaśca grāhyo rudraghaṭodbhavaḥ .. 44 ..

Sixteen of those brahmins, always restrained and calm [were selected]. / 'Offerings are always to be sent by you with devotion, O lord of the earth, / and at the month's end, an ablution born of the Rudra-pitcher must be received [by you]. (44)