One verse

Srimad Bhagavatam 5.19.5

5.19.5

मर्त्यावतारस्त्विह मर्त्यशिक्षणं रक्षोवधायैव न केवलं विभो: । कुतोऽन्यथा स्याद्रमत: स्व आत्मन: सीताकृतानि व्यसनानीश्वरस्य ॥ ५ ॥

martyavataras tv iha martya-siksanam rakso-vadhayaiva na kevalam vibhoh kuto ’nyatha syad ramatah sva atmanah sita-krtani vyasananisvarasya

martya
as a human being
avatarah
whose incarnation
tu
however
iha
in the material world
martya-siksanam
for teaching all the living entities, especially human beings
raksah-vadhaya
to kill the demon Ravana
eva
certainly
na
not
kevalam
only
vibhoh
of the Supreme Personality of Godhead
kutah
from where
anyatha
otherwise
syat
there would be
ramatah
of one enjoying
sve
in Himself
atmanah
the spiritual identity of the universe
sita
of the wife of Lord Ramacandra
krtani
appearing due to the separation
vyasanani
all the miseries
isvarasya
of the Supreme Personality of Godhead

It was ordained that Ravana, chief of the Raksasas, could not be killed by anyone but a man, and for this reason Lord Ramacandra, the Supreme Personality of Godhead, appeared in the form of a human being. Lord Ramacandra’s mission, however, was not only to kill Ravana but also to teach mortal beings that material happiness centered around sex life or centered around one’s wife is the cause of many miseries. He is the self-sufficient Supreme Personality of Godhead, and nothing is lamentable for Him. Therefore why else could He be subjected to tribulations by the kidnapping of mother Sita?