Is the Saum (Fasting) of someone who ate and drank forgetfully while offering fasting of oath expiation invalidated?
Whosoever eats, or drinks forgetfully is exempted by Allah; therefore, he/she shouldn`t break their fast whether it was obligatory, non-obligatory, or expiatory. And Allah Knows Best.
What is teh ruling on thoughtless oath?
One who swears by Allah unintentionally and isn`t determined to fulfill his oath, nothing is due on him. Allah, The Almighty, Says (What means): "God will not call you to account for thoughtlessness in your oaths, but for the intention in your hearts; and He is Oft-forgiving, Most Forbearing." [Al-Baqarah/225]. However, it is dispraised for a Muslim to swear frequently.
Does an internal examination require ghusl?
Ghusl isn't required for making internal examination; however, it invalidates one's fasting. And Allah Knows Best.
Islamic creed is a comprehensive creed, and if there is any defect, the creed of the individual or group is not correct. Is the creed of the Sufis correct or not?
Sufism is the practice of applying knowledge; this is how Al-Imam Al-Sha'rani defined it. If some among them have deviations in creed, it is not permissible to generalize this to all Sufis, as there are those among them who are acknowledged by all scholars for their knowledge and virtue. And Allah The Almighty Knows Best.