Aqeedah comes from the word Aqada which means "to tie something firmly". In the sciences of Islam, Aqeedah refers to all sets of belief that has to be firmly established in the heart, without any wavering or doubt
Abu Obayd al-Qaasim bin Sallaam said, "The one following the Sunnah is like the one clinging on hot coal. To me, following the Sunnah today is better than hitting with the sword in the cause of Allah " [Aqeedat as-Salaf As'haab al-Hadeeth by al-Imam as-Saabooni]