Skanda Purana — Kashi Khanda, Shloka 51
भाजनोपस्थितं दैवाद्भोज्यं नास्यं स्वयं विशेत् । हस्तवक्त्रोद्यमात्तच्च प्रविशेदौदरीं दरीम्
bhājanopasthitaṃ daivādbhojyaṃ nāsyaṃ svayaṃ viśet | hastavaktrodyamāttacca praviśedaudarīṃ darīm
纵使食物因所谓命运而置于器中，也不会自行入人之口；唯凭手与口的用力，方能进入腹中之穴。
Skanda (deduced, Kāśīkhaṇḍa dialogue-context)
Scene: A didactic tableau: a full food-vessel sits before a person; the mouth and hand are shown in purposeful motion, while the belly is depicted as a cave—signifying that effort carries results into fruition.
FAQs
Even when resources appear by destiny, fruition requires deliberate action; effort completes karma.
No specific tirtha is named; the teaching appears within the Kāśī-centered section.
None; it is an instruction in practical dharma—act to realize what providence provides.