مسند أحمد

It was narrated from Hurman bin Aban that `Uthman bin `Affan (رضي الله عنه) said: I heard the Messenger of Allah (ﷺ) say: `I know a word which no one says, sincerely from the heart, but he will be forbidden to the Fire.” `Umar bin al-Khattab (رضي الله عنه) said to him: I will tell you what it is: it is the word of al-ikhlas by means of which Allah, may He be blessed and exalted, caused Muhammad (ﷺ) and his companions to prevail and it is the word of taqwa that the Prophet (ﷺ) of Allah urged his uncle Abu Talib to say when he was dying, the testimony that there is no god but Allah.