A.T. Robertson Commentary 1 Corinthians 10:26

"for the earth is the Lord`s, and the fulness thereof." — 1 Corinthians 10:26 (ASV)

This verse gives the reason for Paul's advice. It is a quotation from Ps 24:1 and was a common form of grace before meals.

Fulness (πληρωμα). Old word from πληροω, to fill, here that with which a thing is filled, whatever fills the earth.