What is the legal status of poetry (Shi'r)?

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Poetry is legally analogous to speech; its good qualities are good, and its bad qualities are bad. The permissibility of poetry is not disputed, as it was practiced by the Companions and scholars. There is a religious necessity for poetry in understanding the language, Arabic grammar, interpreting the Quran and the sayings of the Prophet (peace be upon him), and establishing lineage and history; it is considered the register (Diwan) of the Arabs. Evidence supporting its acceptance includes the tradition stating, 'Indeed, some poetry contains wisdom,' and the Prophet (PBUH) providing a pulpit for Hassan to defend the Messenger of Allah and the Muslims against poets who attacked them. Furthermore, the Prophet (PBUH) permitted Ka'b ibn Zuhayr to recite his poem and told 'Amr ibn Al-Harith to speak when he sought to praise the Prophet (PBUH), responding, 'Speak, may Allah never empty your mouth of good.' The Prophet (PBUH) also permitted his recitation of poetry during the Battle of Hunayn: 'I am the Prophet, there is no lie; I am the son of 'Abd al-Muttalib.'