Chapter 1: The Virtue of At-Tauhid and what Sins it Expiates*
Allah the Most High said,

“Those who believe and do not mix their belief with any Dhulm, for them there is security and they are guided ones.” (6:82) [1]

‘Ubaadah bin As-Saamit (R) narrated that Allah’s Messenger; said,

“Whoever testifies that there is none worthy of being worshipped but Allah, Who has no partner, and that Muhammad is His slave and Messenger, and that ‘Eesa (Jesus) is the Slave of Allah, His Messenger, and His Word which He bestowed in Maryam (Mary) and a spirit (created) from Him, and that Paradise is true, and that the Fire is true, Allah will admit him into Paradise, whatever his deeds may be. [2]

They (Al-Bukhari and Muslim) both recorded this Hadith. They (Al-Bukhari and Muslim) also recorded the Hadith of ‘Itbaan:
“Indeed Allah has forbidden for Hell the person who says: ‘There is nothing worthy of being worshipped but Allah,’ seeking thereby the Face of Allah.” [3]

Abu Sa’eed AI-Khudri narrated that Allah’s Messenger said,

“Musa (Moses) said: ‘O my Lord, teach me something by which I can remember You and supplicate to You.’ Allah answered: ‘Say, O Musa, La ilaha illallah (none has the right to be worshipped but Allah).’ Musa said: ‘O my Lord, all your slaves say this.’ Allah said: ‘O Musa, if the seven heavens and all of their inhabitants besides Me, and the seven earths were in a pan (of a scale), and La ilaha illallah was in (another) pan, La ilaha illallah would outweigh them.”

Ibn Hibbaan and AI-Haakim recorded this, and he (AIHaakim) graded it authentic (Saheeh).
At-Tirmithi recorded a Hadith that he graded good (Hasan), from Anas (who said): “I heard Allah’s Messenger’ ; saying,
“Allah the Most High said, “O son of Aadam! If you came to Me with sins filling the earth, then you met Me without associating anything with Me, I would come to you with its (the earth’s) fill of forgiveness.’