Al-Hadid 57:28

O you who believe, fear Allah and believe in His Messenger; He will give you a double share of His mercy and will give you a light by which you walk, and forgive you, for Allah is All-Forgiving, Most Merciful.

O you who have believed, fear Allāh and believe in His Messenger; He will [then] give you a double portion of His mercy and make for you a light by which you will walk and forgive you; and Allāh is Forgiving and Merciful.

28. O you who believe [in Mûsâ (Moses) (i.e. Jews) and ‘Îsâ (Jesus) (i.e. Christians)]! Fear Allâh, and believe in His Messenger (Muhammad صلى الله عليه وسلم), He will give you a double portion of His Mercy, and He will give you a light by which you shall walk (straight). And He will forgive you. And Allâh is Oft-Forgiving, Most Merciful.[4]

[4] (V.57:28)
(a) Narrated Abû Buradah’s father: Allâh’s Messenger صلى الله عليه وسلم said, "Any man who has a slave-girl whom he educates properly, teaches good manners, manumits and marries her will get a double reward. And if any man of the people of the Scriptures (Jews and Christians) believes in his own Prophet and then believes in me (Muhammad صلى الله عليه وسلم) too, he will (also) get a double reward. And any slave who fulfils his duty to his master and to his Lord (Allâh) will (also) get a double reward." (Sahih Al-Bukhari, Vol.7, Hadîth No.20).
(b) It is obligatory to have Belief in the Messengership of the Prophet (Muhammad صلى الله عليه وسلم).
Narrated Abu Hurairah رضي الله عنه : Allâh’s Messenger صلى الله عليه وسلم said, "By Him (Allâh) in Whose Hand Muhammad’s soul is, there is none from amongst the Jews and the Christians (of these present nations) who hears about me and then dies without believing in the Message with which I have been sent (i.e. Islâmic Monotheism), but he will be from the dwellers of the (Hell) Fire." (Sahih Muslim , the Book of Faith, Vol.1, Chapter No.240) See also (V.3:85) and (V.3:116).

O ye who believe! Be mindful of your duty to Allah and put faith in His messenger. He will give you twofold of His mercy and will appoint for you a light wherein ye shall walk, and will forgive you. Allah is Forgiving, Merciful;