Agniveshyagrihyasutra 2.4.11.5

2.4.11.5

atha śvobhūte ādityavāre āditye 'bhyuditamātre gomayena gocarmamātraṃ caturaśraṃ sthaṇḍilamupalipya madhye svarṇamathavā rajataṃ vā padmaṃ nidhāya

Then on the following day, on a Sunday, just as the sun has risen, having smeared a square sacrificial ground the size of a cowhide with cow dung, having placed in the middle a lotus of gold or silver,