Serving the Deity

Do not eat before the Deity

Do not take prasāda in front of the Deity, and do not eat or serve anything before it has been offered.

The Deity’s hall is for worship, not for meals. Take prasāda in the prasāda hall or at home, after it has been offered. The Nectar of Devotion lists accepting prasāda before the Deity, eating anything that has not first been offered to Kṛṣṇa, and giving cooked food to anyone before it has been offered to the Deity, among the offenses to avoid.

Whose teaching
Vedic scripture
Where it is taught
The Nectar of Devotion, ch. 8: offenses 11, 25 and 27
Source
Vedabase
Do not eat before the Deity · HariHariBol