CC Madhya 3.74

prabhu bale — eta anna nāriba khāite
sannyāsīra dharma nahe ucchiṣṭa rākhite
Word for word: 
prabhu bale — the Lord said; eta — so much; anna — eatables; nāriba — I will not be able; khāite — to eat; sannyāsīra — of a sannyāsī; dharma nahe — it is not the duty; ucchiṣṭa — remnants of food; rākhite — to keep.
Translation: 
Śrī Caitanya Mahāprabhu said, “I will not be able to eat so much food, and it is not the duty of a sannyāsī to leave remnants.”
Purport: 

According to Śrīmad-Bhāgavatam (11.18.19):

bahir jalāśayaṁ gatvātatopaspṛśya vāg-yataḥ
vibhajya pāvitaṁ śeṣaṁ
bhuñjītāśeṣam āhṛtam

“Whatever edibles a sannyāsī gets from a householder’s house he should take outside near some lake or river, and after offering the food to Viṣṇu, Brahmā and the sun (three divisions), he should eat the entire offering and not leave anything for others to eat.”