Is it authentic that if someone recites the last few verses of Aal-'Imraan before sleeping at night, they will get a reward equal to that of someone who prays voluntary prayers the whole night? Please provide detailed information. May Allaah, The Exalted, reward you.

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger. 

What you said was mentioned in a weak narration that was not confirmed as authentic. It was reported by Ad-Daarimi from ‘Uthmaan ibn ‘Affaan.

The verifying scholar, Shaykh Husayn Asad, said, “Its chain of narration is weak because Ibn Lahee'ah is a weak narrator.” 

The Fatwa of the Standing Committee for Issuing Fataawa reads:

Question: “It was said that the Prophet used to recite verses 189 and 200 from Soorah Aal-‘Imraan every night, and Ad-Daarimi reported from ‘Uthmaan ibn ‘Affaan that he said, 'Whoever recites the last verses of Aal-‘Imraan in a night, it will be written for him as if he had prayed the whole night.'”

Answer: “We are not aware of any evidence that the Prophet used to recite verses 189 and 200 from Soorah Aal-‘Imraan in particular every night. As for the narration from ‘Uthmaan it was cited by Ad-Daarimi in his Sunan, and this was ‘Uthmaan’s statement [and not a hadeeth attributed to the Prophet]; Ad-Daarimi said, 'Is-haaq ibn ‘Eesa reported the above statement to us from Ibn Lahee’ah, from Yazeed ibn Abi Habeeb, from Abu al-Khayr, from ‘Uthmaan. Ibn Lahee’ah is a weak narrator, thus the chain of narrators is weak.”

Allaah knows best.