Praise be to Allaah.
Aqeedah refers to those matters which are believed in, with certainty and conviction, in one’s heart and soul. They are not tainted with any doubt or uncertainty.
The Arabic word ‘aqeedah stems from the root ‘aqada, which conveys meanings of certainty, affirmation, confirmation, etc. In the Qur’aan, Allaah says (interpretation of the meaning):
“Allaah will not punish you for what is unintentional in your oaths, but He will punish you for your deliberate oaths (bimaa ‘aqqadtum al-aymaan)…”
Hadeeth means the words, actions, approval or attributes that have been narrated from the Messenger (peace and blessings of Allaah be upon him). A hadeeth may either confirm things that are mentioned in the Qur’aan, such as prayer, zakaah, etc., or it may give details of things that are mentioned in the Qur’aan in general terms, such as the numbers of rak’ahs in each prayer, the thresholds for paying zakaah, the details of Hajj, etc. It may also explain rulings which are not mentioned in the Qur’aan, such as the prohibition on being married to a woman and her (paternal or maternal) aunt at the same time.