SB 4.19.20
atrih sandarsayam asa
tvaramanam vihayasa
kapala-khatvanga-dharam
viro nainam abadhata
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The great sage Atri again pointed out to the son of King Prthu that Indra was fleeing through the sky. The great hero, the son of Prthu, chased him again. But when he saw that Indra was carrying in his hand a staff with a skull at the top and was again wearing the dress of a sannyasi, he still chose not to kill him.