PURPORT
According to Śrīmad-Bhāgavatam (SB 11.18.19):
- bahir jalāśayaṁ gatvā tatopaspṛśya 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.”