18.75 By the grace of Vyasa Sanjaya speaks

व्यासप्रसादाच्छ्रुतवानेतद्गुह्यमहं परम्
योगं योगेश्वरात्कृष्णात्साक्षात्कथयतः स्वयम्

vyāsa-prasādāch chhrutavān etad guhyam ahaṁ param
yogaṁ yogeśhvarāt kṛiṣhṇāt sākṣhāt kathayataḥ svayam

By the grace of Vyasa I have heard this highest secret, this yoga, spoken by Krishna himself, the master of yoga, in person.

Explanation

By the grace of Vyasa.

He credits the poet — the author of the epic this scene sits inside — for the ability to have heard it at all.

A strange and modest moment. The narrator names his own authorial source inside the poem, which is 4.1's lineage acknowledged from the other end.