It is reported on the authority of Abu Hurairah (RA) that the Messenger of Allah (ﷺ) (may peace and blessings of Allah be upon him) made observations like them embodied in the hadith narrated by Yahya bin Muhammad on the authority of 'Ala', and added to it: even if he observed fast and prayed and asserted that he was a Muslim.
Hadith Referenceصحيح مسلم / كتاب الإيمان / 59
Hadith Gradingمحدثین:أحاديث صحيح مسلم كلها صحيحة
Hadith Takhrij«أحاديث صحيح مسلم كلها صحيحة ، انفرد به مسلم - انظر ((التحفة)) برقم (14096) »
This hadith has been transmitted on the authority of Ibn 'Umar but with a slight variation of wording (and the words are):" One of them would be completely submerged in perspiration up to half of his ears."
Hadith Referenceصحيح مسلم / كتاب الجنة وصفة نعيمها وأهلها / 2862