Is it true that Al-Hasan ibn Ali, may Allah be pleased with them both, recited the verse: (That Allah is free from [all responsibility to] the disbelievers and His Messenger.) [Quran 9:3] by lowering the word "His Messenger" (رسوله), and is it correct to say that it was lowered by proximity (al-mujawara)?

The interpretation of the verse (And a proclamation from Allah and His Messenger to the people on the day of the Great Pilgrimage that Allah is free from the idolaters and His Messenger) confirms that the meaning is the disavowal of Allah and His Messenger from the idolaters. The common reading with a dammah on "wa rasuluh" (and His Messenger) is a subject (mubtada') with an omitted predicate (khabar) understood as "and His Messenger is free from them." The reading with a fathah on "wa rasulah" is a conjunction (atf) to the noble name of Allah, which is in the accusative case due to "anna." As for the reading with a kasrah on "wa rasulihi," it is anomalous and impermissible because it suggests that Allah is free from His Messenger, which is false and disbelief (kufr). This anomalous reading was attributed to Al-Hasan (definition) Al-Basri, but it is not authentically reported from him, and it might have been a reason for the emergence of Arabic grammar.