CC Antya 16.96

‘sukṛti-labhya phelā-lava’ — balena bāra-bāra
īśvara-sevaka puche, — ‘ki artha ihāra’?
Synonyms: 
sukṛti — by great fortune; labhya — obtainable; phelā-lava — a particle of the remnants; balena — says; bāra-bāra — again and again; īśvara-sevaka — the servants of Jagannātha; puche — inquire; ki — what; artha — the meaning; ihāra — of this.
Translation: 
The Lord said again and again, “Only by great fortune may one come by a particle of the remnants of food offered to the Lord.”
Purport: 

The servants of the Jagannātha temple inquired, “What is the meaning of this?”

The remnants of Kṛṣṇa’s food are mixed with His saliva. In the Mahābhārata and the Skanda Purāṇa it is stated:

mahā-prasāde govindenāma-brahmaṇi vaiṣṇave
sv-alpa-puṇyavatāṁ rājan
viśvāso naiva jāyate

“Persons who are not very highly elevated in pious activities cannot believe in the remnants of food [prasādam] of the Supreme Personality of Godhead, nor in Govinda, the holy name of the Lord, nor in the Vaiṣṇavas.”