A:
The right `Aqidah is to believe in Allah, His Angels, Books, Messengers, in the Last Day, and the Divine Destination whether good or bad. This was mentioned in the Qur'an and the Sunnah (whatever is reported from the Prophet) and was followed by the Salaf (righteous predecessors) and Imams (rulers) of the Ummah (Muslim nation). There are numerous books that (Part No. 2; Page No. 432) tackle this issue and the best and most useful of which is the Glorious Qur'an where there is true guidance and remedy. Allah (Exalted be He) says:
Verily, this Qur’ân guides to that which is most just and right
These books also include the authorized books of Hadiths such as
Al-Bukhari,
Muslim, Sharh Al-`Aqidah Al-Tahawiyah by
Ibn Abu Al-`Izz Al-Hanafy, books of
the Shaykh of Islam Ibn Taymiyyah and his disciple
Ibn Al-Qayyim, books of Shaykh Al-Islam
Muhammad ibn `Abdul-Wahhab and the books of other authentic scholars.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.