Chāndogya Upaniṣad 6.7.3

6.7.3

taṃ hovāca yathā somya mahato 'bhyāhitasyaiko 'ṅgāraḥ khadyotamātraḥ pariśiṣṭaḥ syāt \
tena tato 'pi na bahu dahet \
evaṃ somya te ṣoḍaśānāṃ kalānām ekā kalā atiśiṣṭā syāt \
tayaitarhi vedān nānubhavasi \
aśāna \
atha me vijñāsyasīti \\607.3\

3. To him he then said: ‘Just as, my dear, a single coal of the size of a fire-fly may be left over from a great kindled fire, but with it the fire would not thereafter burn much—so, my dear, of your sixteen parts a single sixteenth part may be left over, but with it you do not now apprehend the Vedas. (4) Eat; then you will understand from me.’