Nāgasutta

Suttapiṭaka · Saṁyuttanikāya · Sagāthāvaggasaṁyutta · Vol. 15 · Section 420

[420] Then Māra the Evil One, desiring to arouse fear, trepidation, and horripilation in the Blessed One, created the form of a great elephant king and approached the Blessed One. Its head was like a great ariṭṭhaka gem. Its tusks were like pure silver. Its trunk was like a great plough-pole.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 1 other place

Vol. 15 · Section 432 — Sappasutta