patraṁ puṣpaṁ phalaṁ toyaṁ yo me bhaktyā prayacchati tad ahaṁ bhakty-upahṛtaṁ aśnāmi prayatātmanaḥ

"If one offers Me with love and devotion a leaf, a flower, a fruit or water, I will accept it." (Bg. 9.26) Therefore the International Society for Krishna Consciousness has many temples all over the world, and in each and every temple the Lord is offered these foodstuffs. On the basis of His demands, the devotees chant the holy name of the Lord offenselessly and never eat anything that is not first offered to the Lord. The functions of the tongue in devotional service are to chant the Hare Krsna maha-mantra and eat prasada that is offered to the Lord.