[Advaita-l] [Off-topic] Question: Understanding a simile in Valmiki Ramayana

[Murali]

Dear List Members,
Apologies for this off-topic query.
I need help in understanding a simile used early in the Balakhanda of Valimiki Ramayana. In response to Valmiki's questions about a person with a list of superlative qualities, Narada begins by recounting such qualities in Sri Ramachandra's, and then expands on them with some beautiful similes. 
...samudra iva gAmbhIrye dhairyeNa himavAniva|| Balakhanda 1.17||
vishNuna sadrSo vIrye somavatpriyadarSanaH |kAlagnisadrSaH krodhe kSamayA pritvIsamaH || 1.18 ||
dhanadena samastyAge satye dharma ivAparaH |tamevamguNasampannam rAmam satyaparAkramam || 1.19 ||
dhanadena samastyAge - Why is Rama's tyAga being compared to that of Kubera? How are we to understand this comparison correctly? 
Thanks in advance,
Murali Manohar