Were the rules of recitation specific to the Qur’an, or were they applied by Arabs to their speech and poetry?

The rules of Tajwid are established by a continuous, unbroken chain of transmission from the Companions, who received them from the Prophet, peace and blessings be upon him. The Quran is an authoritative proof over all else. The Arabs were familiar with idgham (assimilation) of both types, qalqalah (vibration), the articulation points of letters, and the rules of tarqiq (lightening) and tafkhim (heavy pronunciation). However, tartil (recitation with proper rhythm and contemplation), which includes mudud (prolongations) and ghunnah (nasalization), was not known to them. For this reason, Allah commanded the recitation of the Quran with tartil. Evidence for this is Ibn Mas'ud's disapproval of someone who recited the Quran quickly.