Tafsir of ayah 17:9

إِنَّ هَٰذَا الْقُرْآنَ يَهْدِي لِلَّتِي هِيَ أَقْوَمُ وَيُبَشِّرُ الْمُؤْمِنِينَ الَّذِينَ يَعْمَلُونَ الصَّالِحَاتِ أَنَّ لَهُمْ أَجْرًا كَبِيرًا

Surely this Quran Guides to that which is most upright

(It has been narrated) from Musa Bin Ja’far (as), from his father Ja’far Bin Muhammad (as), from his father Muhammad Bin Ali (as), from his father Ali Bin Al-Husayn (as) having said: ‘The Imam (as) from us is not other than an Infallible. And it is not the infallibility in the apparent nature (as an innocent child) but he is (surely) recognised by it (through his sayings and deeds), so it is due to that that he is not other than an Infallible’.
So it was said, ‘O son of Rasool-Allah (sawa)! So what is the meaning of the infallibility?’ So he (as) said: ‘He holds tightly to the Rope of Allah (Swt), and the Rope of Allah (swt) is the Quran. Both of them will not separate from each other up to the Day of Judgement, for the Imam Guides to the Quran, and the Quran Guides to the Imam, and these are the Words of Allah Mighty and Majestic “Surely this Quran Guides to that which is most upright.” (17:9)

Sanad: Ibn Babuwayh, from Ahmad Bin Muhammad Bin Abdul Rahman Al Maqry, from Abu Amro Muhammad Bin Ja’far Al Maqry Al Jarjany, from Abu Bakr Muhammad Bin Al Hassan Al Mowsaly at Baghdad, from Muhammad Bin Aasim Al Tareyfi, from Abbas Bin Yazeed Bin Al Hassan Al Kahal salve of Zayd Bin Ali, from his father;

Ma`ani Al-Akhbar, Volume 1, Page 132
Tafsir Al-Burhan, Volume 4, Page 539 – See Image