ما الفرق بين الاعتقاد وحديث النفس؟

Belief (I'tiqad) is what the heart firmly assents to, derived from the word 'aqd, which means to tie and bind strongly. Correct Islamic belief is what a person professes to Allah from what the Prophet, peace and blessings be upon him, brought. Anything that contradicts it is a corrupt belief. As for inner thoughts (hadith al-nafs), they are what pass through one's mind without belief or settlement, and Allah has overlooked them as long as they are not acted upon or spoken.