The Gods invited to a great sacrifice, among those invited was Kubera, who was traveling with his friend Manimantha. Manimantha accidentally spat on sage Agastya.
Despite an immediate apology, he cursed him for being killed by a human. It was Bhima, who was going to pick a few Saugandhika flowers for Draupadi in Kubera’s garden, who carried out the curse.
Manimantha did not want to let him in and a fight ensued, which he lost.
Read the story here
http://hindumythologyforgennext.blogspot.com/2012/08/bheema-and-saugandhika-flower-part-1-of.html