Preached at Jetavana to Pasenadi. Pasenadi hints that the Buddha is young and, as compared with other teachers, not fully enlightened. The Buddha explains to him that there are four things in the world which must not be lightly regarded on account of their youth - a noble prince, a snake, a fire, and a holy man (bhikkhu).
It was this sutta which effected the conversion of Pasenadi. S.i.68f.
The Northern books call it the Kumāradrstānta Sutra (Rockhill: p.49).