One verse

Srimad Bhagavatam 9.10.54

9.10.54

एकपत्नीव्रतधरो राजर्षिचरित: शुचि: । स्वधर्मं गृहमेधीयं शिक्षयन् स्वयमाचरत् ॥ ५४ ॥

eka-patni-vrata-dharo rajarsi-caritah sucih sva-dharmam grha-medhiyam siksayan svayam acarat

eka-patni-vrata-dharah
taking a vow not to accept a second wife or to have any connection with any other woman
raja-rsi
like a saintly king
caritah
whose character
sucih
pure
sva-dharmam
one’s own occupational duty
grha-medhiyam
especially of persons situated in household life
siksayan
teaching (by personal behavior)
svayam
personally
acarat
executed His duty.

Lord Ramacandra took a vow to accept only one wife and have no connection with any other women. He was a saintly king, and everything in His character was good, untinged by qualities like anger. He taught good behavior for everyone, especially for householders, in terms of varnasrama-dharma. Thus He taught the general public by His personal activities.