In The Name of Allaah, The Most Merciful, The Bestower of Mercy
Among their [doubts which they portray as truth but are falsehood in reality] is that by merely saying ‘There is no deity worthy of worship except Allaah’, it is enough to enter a person in paradise, even if the person commits disbelief and polytheistic acts. They [hold this view due to their (wrong) understanding of] the Ahaadeeth that have been transmitted regarding this affair – that whoever says that ‘There is no deity worthy of worship except Allaah’, the fire has been made forbidden [for him].
Response to this doubt: The Ahaadeeth that have been mentioned [i.e. regarding this affair] are attributed to a person who says, ‘There is no deity worthy of worship except Allaah’, then he dies upon such a state and did not negate it by committing shirk; rather he said it sincerely from the bottom of his heart whilst disbelieving in [everything] that is worshipped besides Allaah and dies upon this state. It’baan [radiyallaahu-anhu] said [that the Messenger (sallal-laahu-alayhi-wasallam) said], ‘’Allaah has forbidden the (Hell) fire for the one who say, ‘There is no deity worthy of worship except Allaah’ for seeking Allaah’s Countenance (i.e. for Allaah’s sake only).’’’ [Bukhaari’ Hadeeth 425] [Source: Muhaadaraat Fil Aqeedah Wad-Da’wah’ page 22-23. abridged and slightly paraphrased]