The most important point in this hadith is the statement:
"...according to his own opinion ..."
This means the meaning of the whole hadith is if you explain or interpret even a single verse of the Qur'an (or more), without real knowledge (of tafseer), as you like (following your own opinion or mind or hawa or nafs), then you are sinning and doing a big mistake, no matter if you may (by chance or logic etc.) explain or interpret it correctly or not!
This hadith has many backups in the sunnah how ever when we check the sunnah.com site we may find that al-Albani is insisting that it is da'if in all of the narrations!
For example you may find it in Jami' at-Tirmidhi on the authority of ibn 'Abbas and Jundub ibn 'Abdullah. In the last version at-Tirmidhi commented the hadith saying that Suhyal ibn Abi Hazm سُهَيْلِ بْنِ أَبِي حَزْمٍ (one of the narrators) is discussed (means not considered as trustworthy by some scholars) but it was narrated on the authority of people of knowledge among them sahaba who were warning people from interpreting the qur'an without having knowledge of tafsser!
You may also find it in Fadail al-Quran of imam an-Nasa-i in Musnad Ahmad (4 times) in at-Tabarni's al-Mo'jam al-Kabir and in Tafsir at-Tabari, in al-Bayhaqi's sho'ab al-Iman and in other hadith collections and books of earlier scholars! Some of the scholars also pointed at an other da'if narrator called 'Abd al-A'ala a-Tha'labi عبد الاعلى الثعلبي (who appears in the chain of at-Tirmidhi's hadith on the authority of ibn 'Abbas)
Some sources these two fatwas (in Arabic) islamweb #20711 and #328897
and this thread about this hadith.
