SB 3.13.18
ity abhidhyayato nasa-
vivarat sahasanagha
varaha-toko niragad
angustha-parimanakah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
O sinless Vidura, all of a sudden, while Brahma was engaged in thinking, a small form of a boar came out of his nostril. The measurement of the creature was not more than the upper portion of a thumb.