Tafsir of Ya seen 36:69

وما علمناه الشعر وما ينبغي له

And We have not taught him poetry, nor is it suitable for him. Allah tells us that He has not taught His Prophet Muhammad poetry.

وما ينبغي له

nor is it suitable for him. means, he did not know how to compose it, he did not like it and he had no natural inclination towards it. It was narrated that he never memorized a stanza of poetry with the correct meter or rhyme -- he would transpose words or memorize it incompletely. In Ad-Dala'il, Al-Bayhaqi recorded that the Messenger of Allah said to Al-Abbas bin Mirdas As-Sulami, may Allah be pleased with him:

أنت القايل أتجعل نهبي ونهب العبيد بين اﻻقرع وعيينة

You are the one who said: "Do you distribute my booty and the booty of the servants between Al-Aqra` and `Uyainah.'' He said, "It is `Uyainah and Al-Aqra`.'' He said:

الكل سواء

It is all the same. i.e., it means the same thing. And Allah knows best. This is because Allah taught him the Qur'an, which

ﻻ يٲتيه الباطل من بين يديه وﻻ من خلفه

تنزيل من حكيم حميد

(Falsehood cannot come to it from before it or behind it; sent down by the All-Wise, Worthy of all praise). (41:42) This is not poetry, as some of the ignorant disbelievers of the Quraysh claimed; neither is it sorcery, a fabrication or a magic spell, as the misguided and ignorant people variously suggested. The Prophet was naturally disinclined to compose verse, and was forbidden to do so by Divine Law.

إن هو إﻻ ذكر وقرآن مبين

This is only a Reminder and a plain Qur'an. means, it is clear and self-explanatory to the one who ponders and comprehends its meanings, Allah says: