Tirukkural-On Virtue-An Open House Or Hospitality- Kural 82

Marundheninum vaendarpaar ranru

Even the nectar of immortality is not to be consumed,

Without sharing with the guests waiting outside.

All commentators have agreed upon the interpretation of 'saavaa marundhu' as the elixir for immortality, but Parithi's reference to poison itself in this context, is not understandable.

In Puranaanooru we have a passage which is directly relevant.

Amildhum iyalvadhaayinum inidhenath

Thamiyar undalum ilarae

Even if it is the heavenly nectar, they will not have it alone.